I've seen some real fancy trickler mods with belt drives and such even one that was controlled of all things a smart phone. I did this and it works great and I have made several for my friends and they really like to use it. It consisted of a small 1.5-3v vibrating motor, 4" piece of K&S 5/16" thick wall tubing, a small push button switch, a couple of O-rings, 1.5 volt battery holder and a few wired connectors. I didn't mention the tube has a 3/16" hole drilled and the motor side is plugged with a small piece of dowel. A drop of super glue holds the motor in place. I taped the wires from the motor as they are fine as frog hair. Those red connectors are from the RC world and they are called JST connectors. This simple little thing works so well.
