Everything in it, is stuff I had laying around.
The button on top triggers, 4 rgb leds inside of it. Its powered by a jeenode, Yes those are bobbers on the rear antenna. The wheels are two cd's with some 1/8? bearings hot glued between them and wrapped in plastic wire wrap conduit.
I did a quick continous rotation mode to a pair of servos. The front "wheel" is a ping pong ball mounted to a pair of springs.
Over all it tools around good. With a 9v battery as the power source. The sonar just lets it back up a little bit and turn left or right off a random guess.
i found an old cell phone i might use the battery out of that to power. I will upload some more photos of the build when acadian goes to bed