After making Thing-O-Fun's functional differential gear system and playing with it for a while I realized that this thing just had to be motorized. I had a Solarbotics GM9 gear motor lying around and it was a perfect fit. All that was needed was a modified input shaft to match up with the shaft on the gear motor and a base to hold the batteries and power switch.I included the scad file so that you can easily change the switch opening to fit your switch.Watch it in motion at http://youtu.be/bFceF0CeGFk