Wind the magnet wire five to seven times around the battery to form a tightly overlapping coil. Start winding about 3 inches from one end of the wire and leave about 3 inches of wire free at the other end. Slide the coil off the battery.
Wind one of the free wires three or four times around the near side of the coil to hold it together. Leave the remainder of the wire sticking straight out from the center of the coil, like the stick of a lollipop. Repeat this step at the opposite side of the coil so that both sides are tightly bound and the free wires form a straight line that bisects the coil. The finished rotor should look like this: —o—
Hold the rotor upright with one of the free wires on the table. Sand the top of the wire lightly to remove its thin coating of insulation, starting about 1/2 inch from the coil. Hold the wire firmly and sand it carefully to avoid removing insulation from the sides or bottom.
Turn the coil around. Sand the other free wire completely so that no insulation remains, again starting about 1/2 inch from the coil. Straighten and center both wires as necessary.
Put one of the disk magnets inside the plastic cup. Put the other disk magnet against the outside bottom of the cup so that the magnets hold each other in place. Center the magnets to each other and to the bottom of the cup. Turn the cup upside-down so that the exterior magnet sits on top.
Unbend the large loop of each paper clip to form a straight post ending in a small loop. Tape the straight end of one paper clip to the side of the inverted cup — near the top — so that it stands upright over the cup and the small loop faces you. Tape the other paper clip to the opposite side of the cup in the same way.
Rest the rotor’s straight wires in the small loops of the upright paper clips. Adjust the paper clips so that the rotor is level and the coil sits directly over the magnet. The bottom of the coil should be as close as possible to the magnet without touching it. Spin the rotor by hand to make sure it turns easily. If it doesn’t, continue adjusting the paper clips and rotor wires until the rotor spins freely. Add extra tape to secure the paper clips, if necessary.
Tape the black battery lead to one of the paper clips. Tape the red battery lead to the other. Insert the battery into the battery holder. Push the rotor gently to make it spin.