Vibration motors are found in telephones, tablets and other electronic devices. They are available in the market and really cheap:
http://www.aliexpress.com/snapshot/233098463.html?orderId=1125252124

The vehicle in this Thing moves around by vibration. Four little tooth brushes are separated from their holder and placed underneath a platform, containing two vibration motors and two AAA batteries. The motors are designed for 6-9 Volts, but they work nicely at 3 Volts as well. The battery compartment is closed with a lid that is kept in place by a rubber band. The contact points are short M3 screws, fixed with corresponding nuts and washers under which the wiring is clamped. No soldering required. The lid has openings for four 5mm leds.
Switch it on, give it a push and it starts running at an amazing speed. Trying to hit a target at some distance with this interactive Thing, could be a nice game for kids.

To be printed with the cylinders upright.