cad.py (Forrest, David): 4:00 9/18 E15-023
   SketchUp (Kate): 4:30 9/19 E15-023
   SolidWorks (Dawn, Stephen): 9/20 4:00 3-462
   Rhino (Duks, Simon): 9/21 4:00 9-255
   Blender (David) + cad internals/algorithms/formats: 9/24 1:00 E15-135