Well I got my current design/build converted to Autocad. It was no simple task since it contains every thing down to the little rubber gromets on the ACME nuts. Come in at over 1000 parts.
This is a testiment of what you can using simple primitives like cubes and cylanders.
I did an anipath to create this simple animation
http://youtu.be/xI1QVidsCXI