SolidWorks costs a fortune, and not even an evaluation version is availible for download. You may also want to check out these, but dont hope for anything:

http://www.solidworks.com/pages/programs/robotwars/index.htmlhttp://www.solidworks.com/pages/prog...ars/index.html
http://www.solidworks.com/pages/programs/battlebots/index.htmlhttp://www.solidworks.com/pages/prog...ots/index.html

Rhino is also an option, and a much cheaper one too.