Step 1: Parts
Spool of enamel-covered solid-conductor copper wire (you can get this in a set at Radio Shack)
Step 2: Putting it Together
2. Wrap the metal shim in wire. Just wrap and wrap. When I wrapped the wire I used an Ohm meter on the buzzing setting (not sure what the real name of it is, it's the setting where it buzzes when resistance is low between the leads). I connect one end to the metal shaft and the other end to one of the ends of the wire I'm winding. This way I make sure the metal shaft never cuts through the wire and connects to the metal shaft. If it does then I unwind the part I just wound and wind it differently.
3. Connect the ends of the wire to the Arduino
4. Push the sketch and your done.