AutoQ3D is a CAD (computer-aided design) program that allows you to design 2D
and 3D objects. It's available for Windows, Linux and iPad. It's free and
it's also open source, so you can even create and compile your own version of
the program if you want.
http://www.techsupportalert.com/content/2d-and-3d-cad-program-free.htm
