CAD - Design 2D or 3D objects, computer aided design software:
Fusion360, sketchup 123D design, open SCAD, Autocad, Solidworks, Invent, Eagle , 123Dcircuits , etc.
Check here for "free" design software.
Related to CAD are Drawing programs that work on meshs:
Rhino, Maya, Meshmix, Blender, Meshlab, SlicerforFusion360
CAM - This a general classification of software used translate designs into information the mill or printer can understand. Different machines need different CAM:
Replicator 2: Makeware, Replicator G, skienforge, Printrun, Cura slic3r, https://www.simplify3d.com/
Roland MDX: Custom Roland software installed on computers at Makeit Labs imports DXF, STL, BMP, Fusion360 CAM
Sherline: meshcam Fusion360 CAM
Plasma CNC: Custom software installed on computers at Makeit Lab, imports DXF files
Viewers, DRC(design rule check), and assisting tools.
http://circuitpeople.com/ This is a great sanity checker for viewing PCB gerber files before routing or ordering