Free version of Autodesk's Inventor Solid Modeler

Autodesk is giving away a light version of its $5,500 solid modeler.
It does everything that the full Inventor does including parametric 3D
part modeling, automated mechanical drawings, DWG interoperability and
photorealistic rendering but doesn't include assembly modeling. It can
read/write standard Inventor files, STEP, IGES, SAT, DWF, JT, UG-NX,
Parasolid, Pro/Engineer and Granite file formats.

See: <http://labs.autodesk.com/technologies/inventor_lt/>

Roger