Step 1: Get the stuff....
-an old electric 3V motor, mine comes from a pocket fan I bought when I was a kid...
-4 tooth brushes (I got those ones in my hotel in hong kong...)
-a fishing line weight the split type is the simplest I can imagine, but any heavy metal piece the size of a pea will fit, you will just have to drill it.
-RC models glue (stronger for small items, but any strong glue does the same...)
-an old plastic telephone card (not on the picture)
- multi tool
Step 2: Making a vibrating motor.....
chose a piece of heavy metal (pantera works great, but lead is better for this instructable), the more dense it is , the more vibration you will get.
here, I chose an heavy lead fishing line weight from my fishing box....EASY to fasten on the axis of the motor, just crush it between the pliers' jaws.
Step 3: Prepare the other parts.
wrap it inside a layer of duct tape for more strength.......
Step 4: VRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR
really funny, my daughter loves it.