Agree with the comment on SolidWorks: this will be far faster than generating solids with AutoCAD.

An inexpensive way to get SolidWorks is to find someone who can verify they are a student or teacher, then have them buy you the educational version (for about $140) from http://www.journeyed.com/

However, before you buy it make sure the educational version supports what you need.

I think the educational version can export IGES, STL, STEP, or other files that can be imported into rendering software, but you should check on that.

Also, I think the educational version of SolidWorks does include their rendering module.

I’m a principle staff mechanical engineer. I use the pro version of SolidWorks on a weekly basis. Many people feel that SolidWorks is the easiest to learn (and use) full-function high-end 3D CAD package.