Step 1: Gather the Parts
-Neodymium magnets (they don't have to be large; mine are pretty small)
-A LOT of 22 gauge magnet wire (just keep the whole spool with you)
-2N3055 NPN Power Transistor or similar
-A battery and matching connector
-An LED (any color)
-A Reed Switch
-A Zip Tie
-Tape or Glue (or both)
-Bolt that fits in the hole of the Lego piece shown in the photo, and 2 nuts to mount it.
-A resistor (see note).
NOTE: I used a 22 ohm resistor with a 9 volt battery and a green LED. I also used a 1,000 ohm resistor with the 12 volt battery in the picture and a green LED. An exact fixed value for the resistor can not be given because when you run the motor on different voltages and use different LEDs, you have to change the resistor to compensate for the changes. Maybe just using a 5,000 ohm potentiometer would be better. For testing, start with 1K ohms.
One more thing. You may be wondering what the LED is used for. It actually acts as a crude speed indicator. The faster it blinks, the faster your motor is spinning. It is also used for testing, but that is detailed in step 6, so don't worry about that for now.