The tiny “robots” that have been taking the internet by storm are, at a most basic level, they are a motor strapped to the head of a toothbrush. Coin batteries are the power source of choice, because each half of the casing is a terminal and so attaching wires to them is easy. Since the bristles of the toothbrush are arranged at an angle, the vibrating makes the “nano car” move in a random direction. If you want your bristlebot to move forwards, cut the bristles at an angle, as below: