Most of us have seen those inexpensive tops that flash LED patterns when you spin them. How about using a cheap flashlight, a small motor, a short piece of PVC pipe, and a lens to make a neat projectable lightshow?
Any small battery powered motor will work, but I used an eject mechanism motor from a broken CD drive for it's heavy duty cycle and low voltage requirements. These motors are EXCELLENT for all kinds of projects, and the best part is, you can pretty much get them free or next to nothing at any local PC repair shop. They pretty much throw old broken CD drives out (soory, these little gems excite me...lol)!
Anyway, thread the wires through the bulb reflector, and then solder the wires to the positive and negative metal plates on the back of the bulb holder piece. Now reassemble the housing, and hot glue the motor so it's centered and level in the bulb reflector.
The clear cover pops right off of the top (for easy battery replacement). It's a simple job to remove the two or three screws holding the circuit board with the button cells and LEDs from inside. The circuit board has a built in switch that's activated by centrifical force.
Use hot glue to center the circuit board with the LEDs facing UP on top of the motor gear.
Pop a couple of D-Cells in the flashlight and screw the head retaining ring with your modded head assembly back onto the flashlight (minus the clear plastic lens, of course). The top of the motor with the circuit board attached will protrude a bit above the retaining ring. Turn on the flashlight and check out the action!
These tops ARE pretty cool, as the logic chip randomly cycles through about 40-50 different light patterns.
Now hot glue the modded flashlight to one end of your 2" diameter PVC pipe section. I got lucky and had a nice groove on the flashlight's retaining ring that made it quite easy.
The length of the pipe will depend on the focal length of the magnifying lens you use. Here's an easy way to figure it out. Turn on the flashlight and point it at the lens so it shines on a wall. Using a tape measure, Move the lens closer or farther away until the pattern comes into sharp focus. Measure the distance between the flashlight top and the lens, and you've got your length.
Ideally, with a little ingenuity, I'm sure someone could come up with a means of allowing adjustments to the length to llow focusing the light patterns at various lengths. The easiest way would probably be to use two tubes that would fit snugly in one another, but still slide, and attach the flashlight to one tube and the lens to the other.
Now, glue or tape your lens to the other end of the PVC pipe, and you're done!
My kids love this, but I admit to playing with it quite a bit myself... ;) Please feel free to ask questions or suggestions. I love it when you all do that! Check out the video for a nice example of the working lightshow!