About this 3D model

fascinating to watch when animated, It is supposed to work on the principle of a constantly shifting center of gravity – the wheel always wants to turn in one direction; after printing, you need eight 5mm ball bearings balls to turn the wheel; enjoy! http://www.youtube.com/watch?v=1nK2NkoUbes http://www.youtube.com/watch?feature=player_embedded&v=GhR-K10UjnY http://www.youtube.com/watch?v=zqG-TL0WnjE#t=83 http://www.youtube.com/watch?v=287qd4uI7-E http://www.thingiverse.com/thing:44185