Simple DorkBot http://dorkbot.org logo for demonstrating your 3D printer to fellow dorks.
Made with TinkerCad: https://tinkercad.com/things/cpVNbKbsQk5
InstructionsPrints on a 140mm bed if you tilt it diagonally (as it is in the STL file).
Skeinforge complains during slicing, but it prints well enough. The STL from TinkerCad often causes artefacts in the slicing that I don't see in viewers like Blender, so I am tempted to point the finger at Skeinforge.