Linda Taalman has been teaching a 3D printer course at James Madison University
http://educ.jmu.edu/~taalmala/
here is an AMS article on 3D printers
http://www.ams.org/samplings/feature-column/fc-2014-03
here is a wikipedia article on 3D printing
https://en.wikipedia.org/wiki/3D_printing
Here is what claims to be a 3D printing tutorial from Mma:
http://www.wolfram.com/broadcast/video.php?c=317&v=644
I found the following link using ?Export in Mma: guide/3DGeometryAndModelingFormats
http://www.segerman.org/3d_printing_notes.html using Mma with no STL
■ STL is an acronym derived from stereolithography, discussed at Wikipedia:
http://en.wikipedia.org/wiki/STL_%28file_format%29