This is of interest to me as well, as long as it isn't too expensive.
I need a drawing tool that can illustrate geometry (preferably in 3D), geometry parameters, forces, force fields, coordinate systems and also provides advanced typing capabilities. Any suggestions?
VPython? Although it may not be 100% perfect, it is free (yay! very important). I can't think of anything else , but it is a relatively simple program
Wiki: VPython - Wikipedia, the free encyclopedia
Download: Download VPython
Why get VPython?: Why use Visual Python?
Just google VPython and get 213'000 hits.