AutoCAD has an free education version: http://www.autodesk.com/education/free-software/all http://www.autodesk.com/education/free-software/all Very easy to ob

AutoCAD has an free education version: http://www.autodesk.com/education/free-software/all http://www.autodesk.com/education/free-software/all Very easy to obtain, but it can't be used for commercial applications obviously. There's also OpenSCAD (GPL): http://www.openscad.org http://www.openscad.org