Magnet and coil.
The coil contains 12,000 to 14,000 turns of wire and represents one of the more difficult parts of the project to successfully achieve. The strong horseshoe magnet can be purchased from Edmund Scientific Company.
I used the metal lathe in the machine shop to create the Plexiglas spools for the wire coils. I counted the number of turns of wire on the spools by timing the wire-feeding process as I supplied the wire to the spinning spools in the lathe and knowing the spinning rate of the metal lathe vice.