I love bristle and brush bots as introductory electronics lessons, beause they are so much fun to play with. For Halloween I made this easy spider bot for a program at the makerspace. Rather than getting more expensive wrapped batteries with wires attached, I used paperclips as leads.
We'll start by building the spider body. Using your scissors or wire cutters, cut the pipe cleaner into four equal pieces. Twist all four pieces together in the middle, spreading the legs out into a star pattern. If desired, bend the end to make "feet.". Glue the eyes onto the pom-pom. Glue the pom-pom onto the center of the legs.
Next, we'll build the battery pack. Cut a piece of electrical tape about 2 inches long. Starting at one end, place a paperclip. Stack the battery on top of that paperclip. Place another paperclip onto the top of the battery. Wrap the remaining electrical tape around the battery to secure the clips to each side.
Using your cutters, separate the head fo the toothbrush from the handle. If the head has a rubberized surface, you may need to remove it to get good adhesion with the battery and motor. You should choose a toothbrush that has fairly flat bristles, as they make it easier to balance the bot. If your bristles aren't flat, consider using scissors to trim them.
Before hot gluing all of your pieces in place, test with double-sided adhesive foam pieces. It can be challenging to get the balance just right for the best movement, and using foam make is possible to remove pieces more easily. Once you have everything that way you like it, remove the foam pieces, one by one, and hot glue items into place.
Build your stack as such, bottom to top: toothbrush, battery pack, motor (centered), pom-pom spider. Make sure the wires from the motor extend out over the paperclips. The paperclips can face the front or back, as you prefer.
Once your bot is built, it's time to power it up. Simply attach the exposed wire from the red lead to one paper clip and the exposed wire from the blue lead to the other paper clip. The order doesn't matter, though technically the red lead should attach to the positive (smooth) side of the battery. The bot will vibrate either way it's connected.
It can be helpful to wrap the long wires around the body of the spider to keep them out of the way. Use wire strippers to expose additional wire if needed to ensure a good connection. Be careful not to have any of the spider legs touch the paperclips, as the wire in them will conduct electricity and can short the circuit.
Once all the spiderbots are working, test to see how bending the legs can change its movement, or create battle rings out of pipe cleaners and see which spiderbot stays in the longest. Decorate your spider with additional eyes, feathers or glitter paint.