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