Some free 3d programs are SketchUp, MeshLab, Wings3D, Blender, and Sculptris. Blender is notoriously brain-exploding. I've used Wings3D a ton for making sculpties, and it's good - if I used it more often I'd be further along. SketchUp is pretty awesome, and very intuitive.

Sculptris is more than fab but I haven't been able to upload anything from it so far (yes, I'm changing the file type to collada). Since Pixologic recently hired its creator and folded it into its product I suspect that bodes ill for Sculptris. But it's still available.

Labels: mesh