Warning: cd rotors are dangerous! One of mine was cracked and it exploded. Wear safety glasses if you don't want to go blind.
Make this quick and simple gyroscope using a toy motor, cd, and plastic pulley. Please be aware that the speed of the gyroscope is pretty fast even using a single AA battery and it is not suitable for young children.
Watch this video to see it in action:
Step 1: Make the hub for the cd
The hardest part of this project is finding a suitable hub to fill in the hole of the cd. I happened to have some plastic pulleys made for toy motors that almost fit. I had to clip off the outer edge of pulley with some wire cutters and then it fit into the cd hole perfectly.
The second photo shows how I just hotglued the pulley into the cd hole.
Step 2: Fit pulley/cd to motor and add battery
Finally just slide the pulley/cd assymbly onto the motor shaft which should be a tight fit.
I soldered a plug onto the motor but you can just solder two wires to the motor contacts.
I then used some tape to tape the wire ends to the battery but of course a battery box with a switch would work best.
I use just a single battery as the rpm for two or more batteries is very high and makes the cd a little dangerous.
You can probably get an even more gyroscopic effect by gluing two or three cds together for a heavier flywheel (rotor).