I recently at a conference and sat in on a session on 3D printing. There were several materials to choose from now, mostly plastic, but I saw rubber and a few other materials.
There's a sort of "faux wood" material you can print with as well.[1] And there is such a thing as 3D printing with metal also[2], although that can be much more expensive and probably isn't down into the reach of DIY'ers yet.
[1]: http://www.wired.com/design/2012/11/3d-printer-wood-filament...
[2]: http://www.extremetech.com/extreme/143552-3d-printing-with-m...