[lukevanoort]

To me, working with AutoCAD to do anything beyond basic shapes is like trying to change the tire on a cement truck with a shovel. That being said, it can be very quick to work in due to the command line interface. Personally, I would take the time to learn the basics of AutoCAD (AutoCAD and AutoCAD drawing are still relatively common), but invest more of my time in Solidworks or some other parametric 3D CAD program.

For your robot, as long as the parts are not complex 3D shapes, AutoCAD will probably be faster to model in initially; however, if you ever need to change dimensions or something later, Solidworks will be a better choice.