Bristlebots are extremely simple DIY devices that use a vibrating motor attached to a toothbrush to allow it to move across the floor. While they generally move randomly about, if you add pipe cleaners as shown in the video below, they can actually be set to move in different patterns.
This favorite weekend hack combines a vibration motor from the store with the head of a used toothbrush. But if you want a lot of them—for classroom instruction or your own personal swarm—Brown Dog Gadgets has 4, 10, and 25-packs of the needed components available here. They even include googly eyes, which certainly increase the enjoyment factor of these little buggers.
While bristlebots are interesting to show off what can be done just by hacking a few common items together, you can take this concept much further. For instance, seen below is a very large dual bristlebot that can be controlled with simple R/C transmitter:
Or, as seen on Hackaday, you could even add an optical sensor to a ‘bot setup, allowing it to control itself automatically:
