Herbie the Bristlebot
Here is a little bot I made last week. He is a Herbie (original circuit by Randy Sargent) light seeking robot. A very simple freeformed circuit, only a lm386 audio amp, a 7805 linear regulator (to keep from blowing up the lower voltage motors), two photodiodes, a few led's, a resistor, a switch and two vibe motors. I built another herbie about a year ago with the typical motor configuration you usually see, and I like that bot quite a bit. I also made a solar bristlebot / photopopper which I posted here... and well this is a mash-up of those two bots. It works suprisingly well, tracking light and turning is very responsive.
For construction I used 'Plumbers Strap' and rivets. Along with super glue to hold wires and the photodiodes in place. I used double sticky foam tape to fasten the toothbrush heads and the motors. The 'eyes' are subminature panel mount red led's from Radio Hack. The actual eyes are large area photodiodes from goldmine electronics. The motors were scavanged from cell phones.
I have found you dont need a special toothbrush to achieve forward motion, just take regular toothbrushes and bend the bristles back and set a book on it for a while. These toothbrushes were the 6 for a dollar type. The battery fastener is one of those hook and loop (velcro) cable straps for your computer cables. It worked out great.
Anyway, I teach robot classes at the local library, and this is my next project. This guy is the prototype, now I am going to do some work on making the circuit easy to assemble in a library (without a soldering iron).