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Here is another tutorial on hollowing meshes, specifically head meshes to obtain a face shell, but I use this method to hollow out bones as well.
Dr. Mike recently posted a great video tutorial on hollowing a head using Meshmixer: https://www.embodi3d.com/blogs/entry/359-how-to-create-a-hollow-shell-from-a-medical-stl-file-using-meshmixer/.
I tend to go back and forth between Meshmixer and Meshlab for different functions to prep a print, but I like to use Meshlab for hollowing because it's quick and you can easily control how much "external" surface is selected, which is especially handy for models that have highly complex internal structures.
Note that this workflow is also useful if you simply want a 3D model (for viewing/interacting in software, Sketchfab) of a smaller file size where you don't need the internal structures and/or you don't want to decimate the model to achieve a smaller file size.
Here are the steps to hollow a head model in Meshlab. I will post screeshots below which you can also find in the Gallery, https://www.embodi3d.com/gallery/album/73-hollowing-skin-model-with-meshlab/.
Import a model into Meshlab.
Go to Filters --> Color Creation and Processing --> Ambient Occlusion per Vertex.
When the new box opens, check the box to select "Use GPU Acceleration" and click "Apply." The default settings are fine for a first step.
Once you become comfortable with the workflow, you can play around with applying the light from different axes: "Lighting Direction" and "Directional Bias".
You will notice that your model is now colorized from light to dark, with "deeper" areas shaded darker.
On the main toolbar, select the "transparent wireframe" view.
You can now see the internal structures that are shaded completely black.
We can now use the shading values to select the areas we want to remove.
Go to Filters --> Selection --> Select Faces by Vertex Quality. The shading values are stored in the Vertex Quality field of your 3D model, with values from 0 (black) to 1 (white), so we can use these values to select the dark (internal or deep) areas we want to remove.
When the Selection box opens up, slide the "Min Quality" value all the way to 0 (to the left). Check the "Preview" box so that you can see which areas are selected in red.
Adjust the "Max Quality" slider left and right until you see that no external surfaces are selected in red. In the image below, you can see that the bottom edges of the eyelids are still red and some skin below the nostrils is also red. When you find a good value, click "Apply" and Close.
**Depending on the model, it may be difficult to adjust the Max slider to a value that doesn't include parts of the eyelids or nose, but I will explain in Step 6 how you can recover these features. Instead of deleting the selection in Step 5, skip to Step 6.
Once you are happy with your selection from Step 4, you can delete everything selected in red by clicking the button shown in the image below. You can see that the model is now hollow, although there may be some disconnected pieces which we will remove in multiple cleaning steps.
If you think you may have selected some external features in Step 4 that you don't want deleted, instead of deleting (Step 5), you can move the selected (red) areas to another layer. Sometimes with overhanging eyelids or very deeply set eyes, these areas might have the same shading values as some internal structures and can't be excluded from the red.
Go to Filters --> Mesh Layer --> Move selected faces to another layer (if your layer dialog is already open, you can right-click on the model name to access the Mesh Layer menu as well). The layer dialog will open up on the right and you will see the name of your original model as well as the new layer. Use the eye icons to toggle visibility.
The Meshlab selection tools can be used to select the areas from the red you want to keep, then move them to another layer. Right-clicking on a mesh name will open the Mesh Layer menu, from which you can "Flatten Visible Layers"--the layers you want to keep can be kept visible and merged into a new mesh.
This image shows the view from the bottom. The head is empty except for that big flat piece at the top of the head.
As an initial cleaning step to remove small pieces, go to Filters --> Cleaning and Repairing --> Remove Isolated pieces (wrt Diameter). The default size works well, but you can adjust it up to 40% or so to remove larger pieces. This is a deletion function, so the floating pieces will be removed and gone forever! Try to not to adjust the size too high--we'll remove large pieces in step 9.
Step 8 will usually not remove large pieces, especially if you're being cautious and only remove small pieces. To remove larger pieces, go to Filters --> Mesh Layer --> Split in Connected Components. The pieces will drop into separate layers in the layer dialog box on the right, and they will be named CC 0, CC 1, etc. You don't want to apply this filter until you've removed small pieces, or you might end up crashing the program because there are too many pieces separating out! As mentioned above, the Mesh Layer menu can also be accessed by right-clicking on the mesh name in the right-hand layer dialog box.
The largest layer is usually CC 0. Toggle visibility to figure out which layer is the one you want. Left-click on it to highlight it in yellow and then export using File --> Export Mesh as...
I prefer to fill holes (Inspector) and create internal walls (Extrude or Offset) in Meshmixer, so you can now import the hollowed model to Meshmixer to fix it up for printing if needed. You can also use the plane cut tool in Meshmixer to remove the flattened edge at the top of the skin model, or apply Ambient Occlusion again in only the z-direction (see Step 1--"Lighting Direction").
This can be an interative process depending on the complexity of the model you're trying to hollow, but it can save on printing time as well as $$ if you're only interested in the external surface. Play around with lighting directions to select the surfaces you want and as always, SAVE meshes along the way in case the program crashes or you make a mistake!
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Top Orbital and Skull 3D Model STL Files on embodi3D®
In our day-to-day lives, we rely on vision more than any of the other four senses, so it only makes sense that human anatomy has adapted to include several features which keep our eyes safe: tear ducts, eyelids, and of course the orbital bone. The orbit (also known as the "eye socket") provides a rigid form of support and protection for some of the most sensitive parts of the eye including the central retinal artery, maeula, retina, choroid, and sclera.
The orbit has such complex anatomical features that modeling can prove difficult, and in many instances, the finer features of the orbital bone have been simply been averaged out. The orbital structure isn't one bone, but seven: the frontal, lacrimal, ethmoid, zygomatic, maxillary, and palatine, and sphenoid bones. Can you think of any part of the human body where seven bones converge to fulfill a singular purpose?
In recognition of this phenomenal feature of the human anatomy (and one of the most recognizable parts of the human skull), this week's embodi3D® Top Uploads articles, we are featuring several standout uploads — all of which can be used to create an orbital and skull 3D model. As detailed in the scholarly article "Clinical application of three-dimensional printing technology in craniofacial plastic surgery" 3D printing techniques are being used in craniofacial surgeries and especially in reconstruction procedures the require complex modeling. Using the latest 3D printing technology and the STL files converted using democratiz3D®, the contralateral orbit can serve as a point of reference for those in the medical field since the ipsilateral structures taken with a CT scan can be easily converted into an STL file and then fed to a 3D printer. These technologies improve patient consultations, increase the quality of diagnostic information while also helping to improve the planning stage of the surgical process. During surgery, a 3D-printed model of the orbital can be used to orient surgical staff and serve as a guide for surgical resectioning procedures.
While these files are available for free on the website, you must register with embodi3D® before you can begin uploading and converting your own CT scans into STL files as well as downloading and 3D printing anatomical models from other users. Every day the collection of anatomical models grows on the embodi3D® website. This is but one of the many ways embodi3D® is seeking to revolutionize medical practices.
#1. An Awesome Model of the Orbit's Acute Anatomy
The orbits are conical structures dividing the upper facial skeleton from the middle face and surround the organs of vision. Seven bones conjoin to form the orbital structure as we can see in the example below.
#2. A 3D Model of the Orbit's Surface in STL Format
This excellent 3D model of embodi3D® shows the superficial bony margin of the orbit, which is rectangular with rounded corners. The margin is discontinuous at the lacrimal fossa. The supraorbital notch (seen in the image below) is within the supraorbital rim and is closed to form the supraorbital foramen in 25% of individuals. The supratrochlear notch is medial to the supraorbital notch.
#3. A CT Scan of an Orbital Floor Fracture
Hisham published this excellent ct scan on embodi3D®. Direct fractures of the orbital floor can extend from fractures of the inferior orbital rim. Indications for repair of the orbital floor in these cases are the same as those for indirect (blowout) fractures. Indirect fractures of the orbital floor are not associated with fracture of the inferior orbital rim.
#4. A 3D Model of an Orbital Fracture
CT scans with coronal or sagittal views and 3D models help guide treatment. They allow evaluation of fracture size and extraocular muscle relationships, providing information that can be used to help predict enophthalmos and muscle entrapment.
#5. 3D Model Showing an Orbital Fracture
Dropbear upload this excellent example of a right orbit fracture.
#6. An Orbit 3D Model (Printable) Showing Fibrous Dysplasia (FD) for Surgical Demonstration
The FD is a benign slowly progressive disorder of bone, where normal cancellous bone is replaced by fibrous tissue and immature woven bone. This entity constitutes about 2.5 % of all bone tumors.
Choi, J. W., & Kim, N. (2015). Clinical application of three-dimensional printing technology in craniofacial plastic surgery. Archives of plastic surgery, 42(3), 267.
Bibby, K., & McFadzean, R. (1994). Fibrous dysplasia of the orbit. British journal of ophthalmology, 78(4), 266-270.
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This week we would like to share the most downloaded 3D models and resources from our site. These may be good resources for educational purposes as they demonstrate the detailed anatomy of the human body. We have a list of the top human heart STL files and another list of free human anatomy STL files.
The 1st place is for Dr. Mike’s tutorial on how to create 3D printable bone models. 3D printing is an evolving technology that enables the creation of unique organic and inorganic structures with high precision. In medicine, this technology has demonstrated potential uses for both patient treatment and education as well as in clinical practice. Learning how to create 3D models and taking this technology as a great advantage for medical education and practice is important for all of us as physicians and this tutorial makes it easy to learn.
The list also includes other great 3D models, like skull and heart. Let’s then take a look into this ten awesome models. Don’t forget to register in order to download the models, you can do it by clicking here.
1. 2.952 Downloads An improved tutorial that shows you how to create 3D printable bone models even more easily and for free on any operating system. Try it! https://www.embodi3d.com/files/file/115-file-pack-for-3d-printing-with-osirix-tutorial/
2. 913 Downloads 3D printable model of a human heart was generated from a contrast enhanced CT scan. https://www.embodi3d.com/files/file/64-3d-printable-human-heart-model-with-stackable-slices/
3. 893 Downloads 3D printable brain is from an MRI scan of a 24 year old human female.
4. 714 Downloads This full-size skull with web-like texture was created from a real CT scan.
5. 648 Downloads 3D printable model of stroke.
6. 609 Downloads Skull with web-like texture was created from a real CT scan.
7. 422 Downloads Anatomically accurate heart and pulmonary artery tree was extracted from a CT angiogram.
8. 396 Downloads Tutorial: "3D Printing of Bones from CT Scans: A Tutorial on Quickly Correcting Extensive Mesh Errors using Blender and MeshMixer”
9. 392 Downloads Tutorial A Ridiculously Easily Way to Convert CT Scans to 3D Printable Bone STL Models for Free in Minutes
10. 373 Downloads Bony anatomy and skin surface of the L and R feet.
1. Colaco, M., Igel, D. A., & Atala, A. (2018). The potential of 3D printing in urological research and patient care. Nature Reviews Urology.
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Hello the Biomedical 3D Printing community, it's Devarsh Vyas here writing after a really long time!
This time i'd like to share my personal experience and challenges faced with respect to medical 3D Printing from the MRI data. This can be a knowledge sharing and a debatable topic and I am looking forward to hear and know what other experts here think of this as well with utmost respect.
In the Just recently concluded RSNA conference at Chicago had a wave of technology advancements like AI and 3D Printing in radiology. Apart from that the shift of radiologists using more and more MR studies for investigations and the advancements with the MRI technology have forced radiologists and radiology centers (Private or Hospitals) to rely heavily on MRI studies.
We are seeing medical 3D Printing becoming mainstream and gaining traction and excitement in the entire medical fraternity, for designers who use the dicom to 3D softwares, whether opensource or FDA approved software know that designing from CT is fairly automated because of the segmentation based on the CT hounsifield units however seldom we see the community discuss designing from MRI, Automation of segmentation from MRI data, Protocols for MRI scan for 3D Printing, Segmentation of soft tissues or organs from MRI data or working on an MRI scan for accurate 3D modeling.
Currently designing from MRI is feasible, but implementation is challenging and time consuming. We should also note reading a MRI scan is a lot different than reading a CT scan, MRI requires high level of anatomical knowledge and expertise to be able to read, differentiate and understand the ROI to be 3D Printed. MRI shows a lot more detailed data which maybe unwanted in the model that we design. Although few MRI studies like the contrast MRI of the brain, Heart and MRI angiograms can be automatically segmented but scans like MRI of the spine or MRI of the liver, Kidney or MRI of knee for example would involve a lot of efforts, expertise and manual work to be done in order to reconstruct and 3D Print it just like how the surgeon would want it.
Another challenge MRI 3D printing faces is the scan protocols, In CT the demand of high quality thin slices are met quite easily but in MRI if we go for protocols for T1 & T2 weighted isotropic data with equal matrix size and less than 1mm cuts, it would increase the scan time drastically which the patient has to bear in the gantry and the efficiency of the radiology department or center is affected.
There is a lot of excitement to create 3D printed anatomical models from the ultrasound data as well and a lot of research is already being carried out in that direction, What i strongly believe is the community also need advancements in terms of MRI segmentation for 3D printing. MRI, in particular, holds great potential for 3D printing, given its excellent tissue characterization and lack of ionizing radiation but model accuracy, manual efforts in segmentation, scan protocols and expertise in reading and understanding the data for engineers have come up as a challenge the biomedical 3D printing community needs to address.
These are all my personal views and experiences I've had with 3D Printing from MRI data. I'm open to and welcome any tips, discussions and knowledge sharing from all the other members, experts or enthusiasts who read this.
Thank you very much!
This tutorial is based on course I taught at the 2018 RSNA meeting in Chicago, Illinois. It is shared here free to the public. In this tutorial, we walk though how to convert a CT scan of the face into a 3D printable file, ready to be sent to a 3D printer. The patient had a gunshot wound to the face. We use only free or open-source software and services for this tutorial.
There are two parts to this tutorial:
- Part 1: How to use free desktop software to create your model
- Part 2: Use embodi3D's free democratiz3D service to automatically create your model
Key Takeaway from this Tutorial:
You can make high quality 3D printable models from medical imaging scans using FREE software and services, and it is surprisingly EASY.
A note on the FDA (for USA people):
There is a lot of confusion about whether expensive, FDA-approved software must be used for medically-related 3D printing in the United States. The FDA recently clarified its stance on the issue.* If you are not using these models for patient-care purposes, this does not concern you. If you have questions please see the FDA website.
- If you are a DOCTOR, you can use whatever software you think is appropriate for your circumstances under your practice of medicine.
- If you are a COMPANY, selling 3D printed models for diagnostic use, you need FDA-approved software.
- If you are designing implants or surgical cutting guides, those are medical devices. Seek FDA feedback.
*Kiarashi, N. FDA Current Practices and Regulations, FDA/CDRH-RSNA SIG Meeting on 3D Printed Patient-
Specific Anatomic Models. Available at https://www.fda.gov/downloads/MedicalDevices/NewsEvents/WorkshopsConferences/UCM575723.pdf Accessed 11/1/2017.
Part 1: Using Desktop software 3D Slicer and Meshmixer
Step 1: Download the scan file and required software
To start, download the starting CT scan file at the link below. Also, install 3D Slicer (slicer.org) and Meshmixer (meshmixer.com).
Step 2: Open 3D Slicer
Open Slicer. Drag and drop the scan file gunshot to face.nrrd onto the slicer window. The scan should open in a 4 panel view as shown below in Figure 1.
Figure 1: The 4 up view.
If your view does not look like this, you can set the 4 up view to display by clicking Four-Up from the View menu, as shown in Figure 2
Figure 2: Choosing the four-up view
Step 3: Learning to control the interface
Slicer has basic interface controls. Try them out and become accustomed to how the interface works. Note how the patient has injuries from gunshot wound to the face.
- Left mouse button – Window/Level
- Right mouse button – Zoom
- Scroll wheel – Scroll through stack
- Middle mouse button -- Pan
Step 4: Blur the image
The CT scan was created using a bone reconstruction kernel. Basically this is an image-enhancement algorithm that makes edges more prominent, which makes detection of fractures easier to see by the human eye. While making fracture detection easier, this algorithm does unnaturally alter the image and makes it appear more "speckled"
Figure 3: Noisy, "speckled" appearance of the scan on close up view
To fix this issue, we will slightly blur the image. Select Gaussian Blur Image Filter as shown below in Figure 4
Figure 4: Choosing the Gaussian Blur Image Filter
Set up the Gaussian Blur parameters. Set Sigma = 1.0. Set the input volume to be Gunshot to face. Create a new output volume called "Gaussian volume" as shown in Figure 5.
Figure 5: Setting up the Gaussian parameters
When ready, click Apply, as shown in Figure 6. You will notice that the scan becomes slightly blurred.
Figure 6: Click Apply to start the Gaussian Blur Image filter.
Step 5: Create a 3D model using Grayscale Model Maker
Open the Grayscale Model Maker Module as shown below in Figure 7.
Figure 7: Opening the Grayscale Model Maker
Set up the Grayscale Model Maker parameters. Select the Gaussian volume as the input volume, as shown in Figure 8.
Figure 8: Choosing the input volume in Grayscale Model Maker
Next, set the output geometry to be a new model called "gunshot model." Set the other parameters: Threshold = 200, smooth 15, Decimate 0.5, Split normals unchecked as shown in Figure 9.
Figure 9: Grayscale Model maker parameters
When done, click Apply. A new model should be created and will be shown in the upper right hand panel, as shown in Figure 10.
Figure 10: The new model
Step 6: Save the model as an STL file
To start saving the model, click the save button in the upper left of the Slicer window as shown in Figure 11.
Figure 11: The save button
Be sure that only the 3D model, gunshot model.vtk is selected. Uncheck everything else, as shown in Figure 12.
Figure 12: The Save dialog. Check the vtk file
Make sure the format of the 3D model is STL as shown in Figure 13. Specify the folder to save into, as shown in Figure 14.
Figure 13: Specify the file type
Figure 14: Specify the folder to save into within the Save dialog.
Step 7: Open the file in Meshmixer for cleanup
Open Meshmixer. Drag and drop the newly created STL file on the meshmixer window. The file will open and the model will be displayed as in Figure 15.
Figure 15: open the STL file in Meshmixer
Get accustomed to the Meshmixer interface as shown in Figure 16. A 3 button mouse is very helpful.
Figure 16: Controlling the Meshmixer user interface
Choose the Select tool. In is the arrow button along the left of the window.
Figure 17: The select tool
Click on a portion of the model. The selected portion will turn orange, as shown in Figure 18.
Figure 18: Selected areas turn orange.
Expand the small selected area to all mesh connected to it. Use Select->Modify->Expand to Connected, or hit the E key. The entire model should turn orange. See Figure 19.
Figure 19: Expanding the selection to all connected mesh.
Next, Invert the selection so that only disconneced, unwanted mesh is selected. Do this with Select->Modify->Invert, or hit the I key as shown in Figure 20.
Figure 20: Inverting the selection
At this point, only the unwanted, disconnected mesh should be selected in orange. Delete the unwanted mesh using Select->Edit->Discard, or use the X or DELETE key as shown in Figure 21. At this point, only the desired mesh should remain.
Figure 21: Deleting unwanted mesh.
Step 8: Run the Inspector tool
The Inspector tool will automatically fix most errors in the model mesh. To open it, choose Analysis->Inspector as shown in Figure 22.
Figure 22: The Inspector tool
The Inspector will identify all of the errors in the mesh. To automatically correct these mesh errors, click Auto Repair All as shown in Figure 23.
Figure 23: Auto Repairing using Inspector
The Inspector will usually fix all or most errors. In this case however, there is a large hole at the edge of the model where the border of the scan zone was. The Inspector doesn't know how to close it. This is shown in Figure 24.
Figure 24: The inspect could not fix 1 mesh error
Step 9: Close the remaining hole with manual bridges
Using the select tool, select a zone of mesh near the open edge. The Select tool is opened with the arrow button along the left. Choose a brush size -- 40 is good -- as shown in Figure 25.
Figure 25: Choosing the select tool
The mesh should turn orange when selected, as shown in Figure 26.
Figure 26: Selected mesh turns orange.
Next, rotate the model and select a zone of mesh opposite the edge from the first selected zone, as shown in Figure 27.
Figure 27: Selecting mesh opposite the defect.
Once both edges are selected, create a bridge of mesh spanning the two selected areas using the Bridge operation: Select->Edit->Bridge, or CTRL-B, as shown in Figure 28.
Figure 28: The bridge tool
There should now be a bridge of orange mesh spanning the gap. Click Accept, as shown in Figure 29.
Figure 29: The new bridge. Be sure to click Accept.
Next, repeat the bridge on the opposite side of the skull. Be sure to deselect the previously selected mesh before working on the opposite side, as shown in Figure 30.
Figure 30: Creating a second bridge on the opposite side.
Step 10: Rerun the Inspector
Rerun the Inspector tool, as shown in Figure 31. Now with the bridges to "help" Meshmixer to know how to fill in the hole, it should succeed. If it fails, create more bridges and try again.
Figure 31: Rerun the Inspector tool
Next, export your file to STL.
Figure 32: Export to STL
Step 11: 3D print your file!
Your STL file is now ready to be sent to the 3D printer of your choice. Figure 33 shows the model after printing.
Figure 33: The final print
Part 2: Using the democratiz3D service on embodi3d.com
democratiz3D automatically converts scans to 3D printable models. It automates the mesh cleanup process and saves time. The service is free for general bone model creation.
Step 1: Register
Register for a free embodi3D account. The process takes only a minute. You need an account for your processed files to be saved to.
Step 2: Upload the NRRD source scan to democratiz3D.
From anywhere in the site, click democratiz3D-> Launch App
Figure 34: Launching the democratiz3D app.
Fill out basic information about your file. That information will be copied to your generated STL file, as shown in Figure 35.
Figure 35: Entering basic file information
Make sure democratiz3D processing is on. Choose an operation to convert your model. Set threshold to 200, as shown in Figure 36.
Figure 36: Operation, threshold, and quality parameters.
Click Submit! In 10 to 15 minutes your model should be done. You will receive an email notification. The completed model file will be saved under your account. Download the file and send it to your printer of choice!
Figure 37; The final democratiz3D file, ready for download.
That's it! I hope this tutorial was helpful to you. If you liked it, please rate it positively. If you want to learn more about democratiz3D, Meshmixer, or Slicer, please see our tutorials page. It has a lot of wonderful resources. Happy 3D printing!
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So I have seen some questions here on embodi3D asking how to work with MRI data. I believe the main issue to be with attempting to segment the data using a threshold method. The democratiz3D feature of the website simplifies the segmentation process but as far as I can tell relies on thresholding which can work somewhat well for CT scans but for MRI is almost certain to fail. Using 3DSlicer I show the advantage of using a region growing method (FastGrowCut) vs threshold.
The scan I am using is of a middle aged woman's foot available here
The scan was optimized for segmenting bone and was performed on a 1.5T scanner. While a patient doesn't really have control of scan settings if you are a physician or researcher who does; picking the right settings is critical. Some of these different settings can be found on one of Dr. Mike's blog entries.
For comparison purposes I first showed the kind of results achievable when segmenting an MRI using thresholds.
With the goal of separating the bones out the result is obviously pretty worthless. To get the bones out of that resultant clump would take a ridiculous amount of effort in blender or similar software:
If you read a previous blog entry of mine on using a region growing method I really don't like using thresholding for segmenting anatomy. So once again using a region growing method (FastGrowCut in this case) allows decent results even from an MRI scan.
Now this was a relatively quick and rough segmentation of just the hindfoot but already it is much closer to having bones that could be printed. A further step of label map smoothing can further improve the rough results.
The above shows just the calcaneous volume smoothed with its associated surface generated. Now I had done a more proper segmentation of this foot in the past where I spent more time to get the below result
If the volume above is smoothed (in my case I used some of my matlab code) I can get the below result.
Which looks much better. Segmenting a CT scan will still give better results for bone as the cortical bone doesn't show up well in MRI's (why the metatarsals and phalanges get a bit skinny), but CT scans are not always an option.
So if you have been trying to segment an MRI scan and only get a messy clump I would encourage you to try a method a bit more modern than thresholding. However, keep in mind there are limits to what can be done with bad data. If the image is really noisy, has large voxels, or is optimized for the wrong type of anatomy there may be no way to get the results you want.
Very few infectious diseases in recent years have commanded the kind of attention and concern that Zika Virus has. Although Zika outbreaks have been reported in Africa, Southeast Asia and other parts of the world since the 1952, recent announcement by the Center for Disease Control and Prevention (CDC) confirming its link with microcephaly has forced everyone to sit up and take notice. The CDC estimates that the current pandemic is widespread with at least 50 countries reporting active Zika transmissions at this time. Most people with Zika virus infection will not have any symptoms though some may experience mild fever, conjunctivitis, muscle and joint pain, and headaches.
The virus is primarily transmitted by the Aedes mosquito. However, pregnant women may pass the infection to their babies, which may lead to microcephaly, a neurological condition associated with an abnormally small brain in the infant. The condition can lead to birth defects ranging from hearing loss to poor vision and impaired growth. Prompt diagnosis and treatment of Zika virus infections in pregnant women can, nonetheless, lower the risk of microcephaly to a great extent. Researchers have, therefore, put in a lot of time, money and effort to find a solution, and as always, three-dimensional (3D) medical printing and bioprinting technologies are leading the way.
Understanding the Disease
To begin with, 3D printing has played a crucial role in conclusively establishing the link between Zika virus and microcephaly. Researchers at John Hopkins Medicine used 3D bioprinting technology to develop realistic models of brain that revealed how the virus infects specialized stem cells in the outer layers of the organ, also known as the cortex. The bioprinted models allowed researchers to study the effects of Zika exposure on fetal brain during different stages of pregnancy. The models are also helping the scientists with drug testing, which is the obvious next stage of their research.
Zika Test Kit
Engineers at Penn’s School of Engineering and Applied Science, under the leadership of Professor Changchun Liu and Professor Haim Bau, have developed a simple genetic testing device that helps detect Zika virus in saliva samples. It consists of an embedded genetic assay chip that identifies the virus and turns the color of the paper in the 3D printed lid of the device to blue. This can prompt healthcare professionals to send the patient for further testing and to initiate treatment. Unlike other Zika testing techniques, this screening method does not require complex lab equipment. Each device costs about $2, making Zika screening accessible to pregnant women from the poorest parts of the world.
The scientists at the Autonomous University of the State of Morelos (UAEM) in Mexico are relying on the additive printing technology to create a microvalve that may help treat microcephaly in infants. The valve reduces the impact of the neurological disease and slows its progression by draining out excessive cerebrospinal fluid associated with this disorder. It can be inserted into the infant brain through a small incision to relieve fluid pressure and provide space for normal development. Researchers estimate the device will be available for patient use by 2017. These examples clearly demonstrate the impact of 3D printing on every aspect of the fight against Zika virus from diagnosing the disease to treating it. The results have been extremely promising, and both researchers and healthcare professionals are immensely hopeful that additive printing technology will help them overcome the infection quickly and effectively.
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Harvard University researchers have 3D printed the first organ-on-a-chip with integrated sensors. This new technology could revolutionize the biomedical research field, which has relied on expensive and time-consuming animal studies and cell cultures for decades.
Organs-on-chips, or microphysiological systems (MPS), are microchips that recapitulate the microarchitecture and functions of living human organs in vitro. The Wyss Institute at Harvard University explains MPS as follows: “Each individual organ-on-chip is composed of a clear flexible polymer about the size of a computer memory stick that contains hollow microfluidic channels lined by living human cells interfaced with a human endothelial cell-lined artificial vasculature, and mechanical forces can be applied to mimic the physical microenvironment of living organs.” Typically, MPS are made in clean rooms using a complex, multi-step lithographic process. Collecting data requires microscopy or high-speed cameras.
What makes this new MPS different, is the simplified manufacturing process and the integrated sensors. Both improvements were accomplished with multi-material 3D printing. The researchers designed six “inks” that enable integration of sensors. The researchers successfully 3D printed a heart-on-a-chip with integrated sensors. They then used the heart-on-a-chip in various studies, including drug responses. The integrated sensors enable continuous data collection, allowing scientists to study gradual changes over longer periods of time.
Read the research published in Nature Materials or watch this video to learn more:
Photo and video credit: Wyss Institute for Biologically Inspired Engineering at Harvard University
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According to the US Department of Health and Human Services, 22 patients die each day in need of an organ transplant because the demand for organs far outpaces the supply. If the compelling idea of producing 3D printed organs is realized many lives could be saved.
A big challenge in this field is to produce printable material that can support cells and is also permeable to nutrients. A hydrogel is a type of synthetic cross-linked polymer that is highly water absorbent. Hydrogels are commonly used as tissue engineering scaffolds for cells because of their biocompatibility.
This is a hot topic in the field right now, and many people around the world are working on developing new bioprinting methods. A challenge to the development of these methods is how well the printed object corresponds to the plan.
A group of Chinese scientists did a study of how various printing parameters affected printing fidelity. They published their results last week in Scientific Reports, the premier scientific journal Nature brand’s open source online journal.
The printing material or bioink must be liquid before printing and gel after printing. To make their hydrogels, they used sodium alginate (the same material this group used to print vasculature), gelatin, and a solution of calcium chloride as a cross linker.
In order to develop a bioprinting process, they feel it is important to understand the impact of changing the printing parameters including air pressure, temperature, feed rate, and printing distance. Another parameter included the ratio of gelatin and alginate.
Using a lab-built 3D printer, they started out with printing 1D lines on a flat surface, connected at different angles. They moved on to lattice shapes as shown in the image above, looking at how well the lattice maintained its shape with different line spacings. The hydrogel tends to spread somewhat upon printing. The printing surface was cooled so that the gel formed. The experiments also determined the impact of gravity.
They used extrusion based printing as opposed to other types of printing because cells are sensitive to thermal and mechanical stress. They found that the 3D printing process did not damage or kill mouse fibroblast cells suspended in the hydrogel as it only had a slight impact on cell survival.
Finally, the looked at a 3D object with successive printed layers as shown in the figure below.
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A neurosurgeon from Saskatoon in Canada has 3D printed a replica of a patient’s brain to help him plan a complex medical procedure.
Working with a team of engineers, Dr. Ivar Mendez created an accurate replica of the patient’s brain, which will allow him to practice surgery.
Dr. Mendez is the head of surgery at the University of Saskatchewan, and is already familiar with using advanced technologies to improve surgical results. He uses computers in the operating room, and has a medical engineer as part of his surgical team.
However, putting together a 3D brain was a more complicated task, but it would make it possible for him to practice working on some of the smallest components of a brain.
"You can imagine it as having a pea inside a sock or balloon," Mendez told CBC. "It is a complex system.”
What makes the model so valuable is that it’s an exact replica of the patient’s actual brain. If they have a tumor or other abnormality, Mendez and his team can create a replica that includes these unique features.
The patient in question was planned to undergo deep brain stimulation. Dr. Mendez needed to insert electrodes into the brain to help soothe overcharged neurons. He usually plans this kind of surgery using a computer model, but wasn’t successful in this case.
His idea was to position one electrode to affect two target neurons, but the computer model wasn’t capable of this kind of surgical planning. Human brains are particularly complex, which makes it difficult for computers to predict how the tissue will react to certain tools.
“I wanted a way to really, before I did a surgery, to know exactly how this was going to reach the brain and the targets I wanted,” Mendez told The Star Phoenix.
That’s why Mendez decided to team up with the school of engineering at U Saskatchewan, as well as radiology technicians and a neuropsychology specialist. The team worked together to make the MRI data understandable to the 3D printer.
The 3D model took 7 months of planning before a prototype was created. It was printed using a transparent material similar to rubber, that allows surgeons to see all the internal structures of the brain as well. Mendez said it also feels fairly similar to an actual human brain.
"I'm a neurosurgeon but I'm also interested in art. To me, this was an object of beauty,” he said.
Dr. Mendez believes the development of the technology will bring new opportunities for surgical practice.
"I envision that in the future we may be able to do procedures that are very difficult or impossible today," he said. "I feel that in the next 20, maybe 25 years, we will be able to print biological materials. We may be able to print organs."
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Much of the press for medical 3D bioprinting has revolved around recreating parts of the human body for medical transplants, implants, and reconstructive surgery. We often find these stories easy to relate to, with visuals that help us understand the benefits of each bioprinting solution.
However, another important aspect of bioprinting that may not be as obvious is its potential contribution to early-stage disease research. This type of research occurs in the laboratory, and focuses on how our cells (the tiny building blocks that make up every part of our body) function and interact during diseases. 3D bioprinting could present a step forward in how researchers construct experiments that help them understand disease.
One of the crucial steps to understanding each type of cancer is figuring out how it communicates with other cells, and what it is saying. Cells in a tumor may talk to cells from within the same tumor, or surrounding healthy cells, and all of this communication could be important for cancerous cells to grow and spread. Thus understanding how cells interact is an important step towards blocking this communication using medical treatments.
To easily set up experiments in the lab, researchers use cancer cell lines - cells which have been taken from tumors and trained to grow in the lab. These cell lines are grown in a single layer, and although this makes it easier to keep them happy, it is quite different to the way cells are arranged in our bodies, i.e. in multiple layers in a 3D space.
3D Bioprinting Cancer
With so many important functions of cancer due to the communication with other cells, it is beneficial for scientists to perform experiments on cancers that are as similar as possible to a living patient. Last year, researchers at the University of Connecticut and Harvard Medical School addressed this, published a review of 3D bioprinting focusing on its potential advantages for cancer research in the lab.
Cancers are a prime candidate for 3D bioprinting - many cancers exist as clumps of cells that lack specific structures, and thus do not require the typical scaffolding that bioprinting organs like ears or bones requires. By layering cells in 3D instead of 2D, a 3D printed tumor is better at replicating the structure of a tumor in a typical human body, and communication between cells in all directions can be achieved.
3D bioprinting also offers the possibility of mixing multiple cell types. This is important because cancer cells communicate not only with each other, but also healthy cells - for example, melanomas interact with surrounding skin cells. In fact, even within a tumor there may me multiple "versions" of cancer cells, all having different things to say each other. Since bioprinting multiple cell types is relatively simple, it is possible to recreate not only tumors themselves more effectively, but also their surroundings.
Current research already feeds into this, as there are already many different types of cancer cells available, and established techniques for getting them into a liquid form for 3D printing.
Customizable, reproducible experiments
It is incredibly important that the results of any research be reproducible, not only within a research group but also between research groups across the globe. Since bioprinting is done using 3D computer models, these can be easily distributed to other researchers. And with the ability to customize the construction of a tumor completely using bioprinting, scientists can validate their results and move faster to obtaining medical solutions.
One of the greatest challenges could be integrating 3D printing medical laboratory techniques that have been established for decades (the first cancer cell line was created in the 1950's). Luckily, companies like Biobots are capitalizing on this gap in the market, building accessible 3D bioprinters with standardized components. And repositories like Build With Life will hopefully hold not only bioprinting designs, but also important protocols that merge current medical research standards with 3D printing technology.
The utilization of bioprinted cancers could be important to the development of new medical treatments. By understanding the interactions between cancer cells and healthy cells in all dimensions, researchers can gain insights into the successful treatment of these cells. And all of the techniques mentioned above could be extended to a range of other diseases. Organovo has already capitalized on this idea, 3D printing liver cells for scientific testing.
One could even predict that, in the same way as 3D-printed organs of specific patients are being used to plan for surgery, 3D printed recreations of patient's tumors or diseases may be able to help tailor the most effective treatment for that patient. The future for integrating bioprinting into the workflows of laboratories around the world seems bright, and could offer faster and more accurate methods for carrying out early-stage research in cancer and many other diseases.
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The utility of modern three-dimensional printing techniques for bio-medical and clinical use has been demonstrated repeatedly in recent years, with applications ranging from surgical modelling to tissue engineering and beyond.
Despite the promise and potential of three-dimensional printing methods, impediments to their widespread clinical uptake still remain. Many of the printers used for medical applications are highly specialised pieces of equipment that require trained operators and controlled operational conditions as well as potentially costly and unique raw materials. These factors can result in high production costs, and the necessity of dedicated sites which can in turn lead to delays between fabrication and clinical application.
Recent work by engineers and researchers at Zhejiang University in China has shown that desktop 3D-printing techniques may represent a more practical alternative for certain clinical tasks.
Desktop 3D printers may cost as little as $500, much less than the $15,000–30,000 machines routinely used in academic institutions. As well as the lower costs, Desktop 3D printers are considered to be much easier to operate. An Liu and co-workers tested the potential of these machines to fabricate bio-absorbable interference screws, used to secure hamstring tendon grafts commonly utilised to repair damaged anterior cruciate ligaments (ACL).
A screw-like scaffold, made from the same polylactic acid filament commonly used for conventional bio-absorbable screws, was printed using fused deposition modelling techniques then coated with hydroxyapatite (HA) to improve its osteoconductivity. The construct was also coated with mesenchymal stem cells, as these cells are widely considered to be of therapeutic value for anterior cruciate ligament regeneration.
A 3D porous structure is considered to be valuable to bone ingrowth into the screw, as this supports the cellular migration and mineral deposition, as well as vascular development, all required as the screw is incorporated into a patient’s bone. Conventional methods have struggled to control to formation of these structures, but by using 3D-printing techniques they can be easily manipulated by surgeons and specialists alike.
Once fabricated the 3D-printed screws were tested upon anterior cruciate ligament repairs in rabbits for up to three months. Magnetic resonance imaging showed that all of the 3D-printed screws were correctly positioned in the bone tunnel without any breakage or major complications, and that over the course of twelve weeks they appeared to incorporate into the bone tissue.
The approximate cost of a 3D printed bio-absorbable screw was 50 cents using industrial grade polylactic acid, and it is estimated that this equates to less than 10 USD using medical grade materials
The successful manufacture of a functional surgical device using desktop 3D printing technology demonstrates the potential for in situ fabrication at the clinic and opens up a range of in-house manufacturing possibilities to clinical staff, circumventing the requirement for costly equipment and bespoke materials as well as trained specialist operators.
3D Printing Surgical Implants at the clinic: A Experimental Study on Anterior Cruciate Ligament Reconstruction. Sci Rep. 2016 Feb 15;6:21704. doi: 10.1038/srep21704
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Many doctors these days are now including 3D printing as part of their many surgical procedures. Dr. Jamie Levine from NYU Langone noted that there is a paradigm shift when it comes to doing surgical procedure in terms of using and relying on 3D printing.
A lot of hospitals all over the United States have already embraced 3D printing to create tools, models or craft tissues used for surgery. One of the hospitals that are leading the paradigm shift is the Institute for Reconstructive Plastic Surgery at NYU Langone. The surgeons from NYU Langone use special printers to create tools and 3D models that can save doctors from performing long and expensive surgeries. In fact, the hospital is able to save $20,000 to $30,000 for every reconstruction that the do.
The use of 3D printing in medical technology is very promising. In fact, the Food and Drug Administration has already approved the creation of 3D printed pills and vertebrae. There are also many researchers all over the world working with 3D printed organs to be used in organ transplantation.
Although medical-grade 3D printers still remain expensive, they can make infinite types of objects like surgical tools, anatomical models and other devices. Fortunately, there are now many companies that are developing cost-effective printers thus the cost is targeted to go down in the future.
There is a wide potential for innovation when it comes to using the 3D printing technology. With this technology, it is no wonder if many hospitals all over the world will rely on 3D printing technology to treat different diseases.
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Every 3D printing case is different, and must be tailored for the individual patient’s specific clinical condition, anatomy, and imaging techniques.
A 47 year old woman with a renal mass was being evaluated for surgical treatment planning. A urologist familiar with my current 3D printing work requested a 3D printed model of the kidney. The purpose was to help demonstrate the anatomy of the mass with respect to the renal hilum, to help determine if a partial nephrectomy was possible, or if a total nephrectomy was required.
The patient had a documented reaction to radiographic iodinated contrast, and therefore an MRI was performed instead of a CT scan. The scan was performed on a 1.5 T GE Signa Excite system. The data set from a coronal 3D gradient echo pulse sequence acquisition was chosen because it best visualized the tumor encroachment into the renal sinus.
The 3D model was created from segmentation of the kidney from the 3D gradient echo acquisition. The renal parenchyma was then made into the digital 3D model, leaving the mass as negative space. This was then printed to demonstrate the entire kidney. An additional 3D model was created showing a bisected view of the kidney along the coronal plane. This was done to see which model would be of more utility.
The patient’s DICOM image files from the MRI were processed using the Materialise Innovation Suite’s Mimics and 3-matic software.
Initially I used the Mimics software segmentation tool to segment the normal renal parenchymal tissue. This left a filling defect where the mass was. This negative space was useful for demonstrating the extent of the tumor.
Using the 3-matic application I then took the 3D digital representation and created a model cut in the coronal plane. This helped better define the extent of the tumor invasion into the renal hilum.
Both the full kidney and the coronal bisected models were printed for the surgeon and the patient to review. The STL (stereolithography or standard tesselation language) files generated for the 3D models were then imported into both the Cura and MakerBot slicing software applications to generate the gcode for the Ultimaker 2 and .x3g file for the MakerBot printers.
Fused filament printing of the full kidney using Acrylonitrile Butadiene Styrene (ABS) on the MakerBot Replicator 2X Experimental Printer and sectioned kidney in Polylactic Acid (PLA) on the Ultimaker 2 printer.
In general I prefer PLA to ABS. With PLA there is less shrinkage and warping of the material during the printing process. PLA is of plant based origin (here in the US it is derived from corn starch) and can print lower layer height and sharper printed corners. PLA, a biodegradable plastic is used in medical devices and surgical implants, as it possesses the ability to degrade into inoffensive lactic acid in the body.
ABS is a petroleum-based recyclable non-biodegradable plastic. Unfortunately emits a potentially hazardous vapor during printing. The Replicator 2X however is optimized for ABS. http://pubs.acs.org/doi/pdf/10.1021/acs.est.5b04983
For more information about PLA/ABS see http://3dprintingforbeginners.com/filamentprimer/#sthash.p07fHBmh.dpuf
The urologist showed the models to the patient, and it help to convince her of the necessity of a total nephrectomy, rather than a partial nephrectomy.
Although the printed models showed the extent of the tumor invasion adequately for both the urologist and the patient to visualize, the models did not differentiate the mass from the renal sinus.
To better demonstrate the tumor invasion, a new model with two different color filaments was created. Hand segmentation of the 3D model of the mass was performed due to the limited tissue contrast between the mass and the surrounding soft tissue structures. Creation of two separate segmentation files and 3D models was made in Mimics.
This was then exported into 3-matic for local smoothing. Two separate STL files of both the mass and kidney were generated. The combined model was then bisected in the coronal plane and the additional two STL files were again generated.
Once the combined STL files were imported into the MakerBot software, they were repositioned on the build plate in an orientation to optimize the printing process. The STL models were positioned on the bed, above a ring spacer file. This is necessary for the proper printing contact. The model was oriented to minimize the amount of printing support structures.
When using the two filament colors, “purge walls” are generated by the software to help eliminate the small threads of filament from one color being deposited when the next color is laid down.
The two filament model enables the surgeon and the patient to better visualize the extent of the tumor invasion, clearly demonstrating normal from abnormal tissues.
Getting from DICOM to 3D printable STL file in 3D Slicer is totally doable...but it is important to learn some fundamental skills in Slicer first if you are not familiar with the program.
This tutorial introduces the user to some basic concepts in 3D Slicer and demonstrates how to crop DICOM data in anticipation of segmentation and 3D model creation.
(Segmentation and STL file creation are explored in a companion tutorial )
This tutorial is downloadable as a PDF file,
or can be looked through in image/slide format here in the blog
Nice review paper on Medical Applications for 3D Printing: Current and Projected Uses:
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This a video demonstrating the use of Mimics software to convert patient dicom images into 3D printable files. Mimics software has many great features to improve and ease workflow. Like other software programs most segmentation and exporting can be accomplished in 15 minutes.
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The Coalition for Imaging and Bioengineering Research (CIBR) is a dedicated partnership of academic radiology departments, patient advocacy groups, and industry with the mission of enhancing patient care through advances in Biomedical Imaging. My good friend and colleague Dr. Beth Ripley and I recently participated in the sixth annual Medical Technology Showcase at Capitol Hill organized by CIBR, representing the Department of Radiology at the Brigham and Women’s Hospital (BWH) where we emphasized the importance of 3D printing in healthcare.
The annual Medical Technology showcase aims to bring examples of medical breakthroughs in imaging and bioengineering to members of congress and demonstrate how these advances are impacting patient care. In addition to educating policy makers and the public about innovative imaging technology, the event demonstrates the value of NIH funded academic research and the importance of collaborations between academia, industry and patient advocacy groups.
Our display booth comprised of the Department of Radiology at BWH, the Lung Cancer Alliance, and Fujifilm was a hit among attendees and we were pleased to see the level of interest in medical 3D printing. We displayed 3D printed models that have been used for different clinical applications and our booth partners from Fujifilm demonstrated Synapse 3D, a software that allows conversion of 2D image data from CT/MRI into 3D printable files.
Our goal was to demonstrate the importance of 3D printing in pre-surgical planning and how it can benefit patients by allowing surgeons to devise a patient specific treatment strategy and minimize post-surgical complications. Sheila Ross, a lung cancer survivor and patient advocate from the Lung Cancer Alliance emphasized how 3D printed models can give patients and their families a better understanding of the planned procedure.
A lung model from Fujifilm demonstrating a nodule (green) and surrounding bronchioles
The Lung & Brain cookies might have been slightly more popular than our 3D models
It is our hope that more funding and resources will be allocated to investigate innovative medical technologies such as 3D printing, which can then be translated to impact patient care. In order to transform 3D printing from being a fad, to a mainstream tool that fosters precision medicine, evidence based benefits of its different applications will need to be demonstrated in clinical trials which will require funding.
Tatiana Kelil, MD
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3D printing has been integrated into the surgical procedures of many physicians, as it has proved very useful in the planning stages of a surgery. It allows doctors to operate with more accuracy and precision by providing a means for surgeons to become acquainted with three-dimensional models of their subjects beforehand.
These models provide a holistic view of the part of the body under examination, which affords the surgeon time to assess the model and make changes in their surgical procedures or recommendations as required. Furthermore, viewing a 3D representation is far superior to that of a CT scan or MRI, as those technologies use flat images that are often difficult to read. A 3D model provides a more realistic view of the subject that is easier to understand. This ultimately gives the surgeon a greater understanding of the anatomy and allows practice before attempting surgery.
Dr. John Meara, plastic surgeon-in-chief at Boston Children's Hospital explained to the Boston Globe that, “In the past, sometimes you had to make many incisions in the operating room. Now I’m making those decisions on a model ahead of time.” By doing this, the doctor is able to reduce operating time and improve recovery time as the patient’s body experiences less trauma during surgery.
Before surgery, the 3D model can also help communication with patients, as the doctor can use the model to explain exactly how the procedure will take place. This increases the patient's trust and further improves the medical care and attention received by the patient.
Affordability Contributes To Increasing Medical Use Of 3D Printing
Surprisingly, 3D printing systems are not as expensive as one would think, and in fact are quite affordable, starting as low as a few thousand dollars for a basic 3D printer. Naturally, more sophisticated models fetch a higher price, but overall the cost of this technology is not insurmountable. This presents the opportunity for 3D printing systems to be used on a wider scale, and ultimately become as common a tool in the medical field as a stethoscope.
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It seems that there is no end to the animals that will benefit from 3D printing and now the process has become so common place it is child’s play. Stumpy came to the Oatland Island Wildlife Center in Savannah, Georgia with a bad infection to his right front leg. In order to save the 12 year old box turtle veterinarian Lesley Mailer amputated the leg. Stumpy lived, but had a very hard time getting around without his front leg. Luckily for Stumpy, Lesley Mailer remembered her daughter mentioning a 3D printer that her 5th grade class at May Howard Elementary was working with. So Mailer contacted the school about creating a new leg for Stumpy.
The school took up the call and choose a few students who were interested in 3D printing and/or animals to work on the project. Six students and a teacher went to work right away to learn about box turtles to understand what Stumpy needed in a new leg. The students were eager to learn and help Stumpy, they spent time after school and during their lunches to design the new leg. Using 3DTin to create 15 prototypes over a month of development the students created a leg that they thought would work for Stumpy. Mailer was just as excited as the students and invited all of them to watch as Stumpy was fitted with his new leg. With just a few minor alterations, Stumpy’s new leg fit perfectly. Now this little box turtle can live out the next 20 to 30 years moving around just as easily as any other turtle. But that doesn’t mean these dedicated students are taking a break, they intend to improve upon their design this year.
Main Image Credit: www.3dprint.com
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