This is a thing that vibrates, and it's a robot. It's very simple to build.
Step 1: Step 1: Make the Circuit
Make this circuit with three motors, a battery, and a switch.
Step 2: Step 2: Tape It on Something
Tape the circuit on something and attach the motors on the sides. I used a piece of cardboard.
Step 3: Step 3: Attach Things and Turn It On
Attach things to the motors to throw them off balance and turn it on. I used a pipe cleaner and a straw.