Parts Required: Project enclosure (@ Radioshack for $5.49), cheap flashlight, Xbox Controller Rumble Motor (or any motor with an offset weight), 2 AA Battery holder (with positive and negative outputs), AA Batteries, Wire (any old wire you have laying around will work).
Step 1: Remove Switch/Button From Flashlight
Step 2: Begin Soldering Your Connections
Step 3: Hot Glue the Connections
Step 4: Cut a Hole in the Enclosure for the Button
Step 5: Begin Gluing in Your Parts.
1) The switch - the switch will be glued in to the hole you created just put two dots of glue where it wont hurt anything and fit it right in the hole. Hold for a couple of seconds to let it dry.
2) The motor - glue the motor somewhere it is not going to hit on anything for me the best place was the top next to the switch. Put A LOT of glue because this part will have a lot of movement which will cause it to fall if there isnt enough glue, but be sure not to get any inside the motor.
3) The Battery Box - put the battery box in a place where you can easily access it for me the best place was the metal plate in the base of the enclosure. Put a decent amount of glue on this and center it where it wont hit the sides when closing the box.