When starting a project it is often easier and cheaper to start with an existing product. In this case a Radio Shack HexBug toy was the base. Some new electronics allows this robot to learn some new tricks.

"The Hexbug sold by Radio Shack is a tiny robotic insect with very simple reflexive “reverse-turn upon obstacle” response. Interesting, but it quickly gets old. How about giving it a real brain? I created a replacement PC board using a PIC microcontroller, and wrote code to give it much more personality. It can now avoid obstacles (as stock), blink, ‘sing’, dance, detect light, check if its batteries are low, and go into a very low power sleep state"

Thanks Mredison