PyCAM

Overview
Mentioned in Neil Gershenfeld's book Fab: The Coming Revolution on Your Desktop--from Personal Computers to Personal Fabrication, the program has since undergone extensive development.

Available from Sourceforge, along w/ a User manual.

Updates have been happening at: https://github.com/SebKuzminsky/pycam

Mac OS X
Note Mac-specific issues here. See also Fast pyCAM on Mac Using Homebrew

=Tutorials=

https://crxguy52.wordpress.com/2016/05/03/pycam-and-cnc-machining/

Video Tutorials
Posted by user alpha in video: PyCam adding depth for gravures:

Vimeo
and more on Vimeo:


 * PyCAM #1: Generating a toolpath for a 2D model
 * PyCAM #2: Using multi-layered 2D models