Homemade robots are a great way to experiment with a variety of arts and sciences, and learn more about the laws of robotics without having to shell out thousands for a degree in robotics. In fact, with the right project, you can use your robots to entertain your pets, or even your kids. A robot, by definition, carries out a task automatically. With a few simple tools and some basic materials, you can build a scooting, ricocheting robot in under 15 minutes.
Snip the bristled head from the toothbrush with the scissors, leaving about a 1/3 inch of neck still attached.
Lay a strip of double-sided sticky tape across the flat top of the toothbrush head, resting on its bristles.
Attach the cell phone motor to the sticky tape, with the turning shaft facing away from the remaining neck of the toothbrush. Make sure that the head of the motor won't impact the toothbrush at all when it turns before securing it to the sticky tape.
Lay one of the motor's wires down flat against the sticky tape, and stick the coin-cell battery on top of it firmly.
Activate your robot by bending the motor's second wire down to touch the top of the battery. The motor will fire up and vibrate your robot rapidly across any smooth surface it's set on.
If your robot overbalances when activated, try trimming the neck a little more. Also, make sure your components are centred on the sticky tape. Cell phone (or pager) motors are required, as they have an unbalanced turning shaft, which creates the vibration when activated. You can buy these pre-isolated from websites like eBay, or you can scavenge them from any cell phone or pager you have.