Good video about CAM software that is “free”. In this case FreeMILL. I haven’t heard of FreeMILL til now, but it sound like its worth checking out. From listening to the video, it sounds promising for trying out. Maybe not so much for general use. Pycam, also reviewed, seem to fair OK.
http://www.instructables.com/id/Intro-to-Free-3D-CAM-Options-pt-1/