Useful when you're outside your maker den and need a quick way to entertain adults and kids.
Step 1: What You Need
1. Handheld battery operated fan - this provides the motor, switch and battery case
2. Scrubbing brush
3. A small nut and bolt - this doesn't have to be very big, a tiny mass is all that's needed to make a vibrating motor, even if you use a large motor instead of tiny pager motor. The one used here is an M3 (a 2-56 nut and bolt would also work fine).
All of these can be found at dollar stores.
You're going to be putting the nut and bolt at the end of a spinning motor, and improperly secured parts can cause the nut and bolt to fly and put someone's eye out. Ensure that everything's held on tight before turning on the motor, and wear safety glasses if you can.
Step 2: Make Your Vibrator Motor
Insert the bolt through the hole and fasten it with the nut securely.
Turn on the motor. If it seems to struggle even with fresh batteries, that's an indication that you're using too much mass. Switch to a smaller nut and bolt.
Step 3: Attach the Fan to the Brush
The fan shown here comes with a cord, which was used to strap the fan onto the brush.
Play around with the orientation of the fan relative to the brush, as the orientation will affect how the brush moves. Try some non-symmetric ways of mounting the fan as well, for instance at a diagonal or crosswise to the brush.
Step 4: Test and Trim
Trimming the bristles can "force" the bristlebot to go in straighter lines. There's no rule for this - just trim and test and trim and test until you're satisfied.
Step 5: Experiment!
Periodically you'll need to re-strap the fan onto the brush, particularly if you're just tying it on with rubber bands or string. For a more secure method, use a hot glue gun or tape. A dab of glue around the nut and bolt won't hurt as well.
With this basic design, you can do many other things:
1 - use straws, sticks and other construction materials to decorate your bristlebot, build outriggers, or build bumpers.
2 - Make a simple cardboard racetrack and have a bristlebot race.
3 - Make a simple ring and have a bristlebot sumo tournament.
4 - Strap a felt-tipped pen to the bristlebot and let it scribble.