A vibrobot is perhaps one of the quickest and easiest bots that you can build. In almost no time you can make a fun little bot that makes its ways to and fro across the floor. It is so easy, in fact, that it wouldn't be hard to make a few at once. And then, you can have your own mini private army of vibrobots to do your bidding (assuming that your bidding is to have a bunch of tiny little bots moving randomly to and fro).
Step 1: Go Get Stuff
Step 2: Strip Wires
Trim the wire leads of the vibrating motor shorter. Strip away a bit of the protective jacket to expose the copper wires.
Step 3: Solder
Solder the red wire of the 2032 battery holder to the positive pin of the battery holder.
Solder the black wire to the ground (minus) pin of the battery holder.
Step 4: Cut
Use your diagonal cutters to cut the toothbrush head from the toothbrush handle.
Step 5: Hot Glue
Hot glue the motor and battery holder to the flat plastic part of the the toothbrush head.
Step 6: Power!
Insert the 2032 battery and watch it go.