Step 1: Parts
K'nex (can be substituted with any other structure-building thing)
Wire (Hookup, and stranded wire)
Cardboard, Plastic, or similar
Aluminum Foil (Conductive ink of some kind is a preferable substitute. I didn't have any.)
Wood or something to form a base
Step 2: Foil
If you are using conductive ink, skip this step.
First, trace a circle in the foil.
Next, cut it out (carefully as foil has a tendency to tear).
You will need to cut two out.
Then, cut out a hole in the center of each circle.
Cut out two smaller ones to fit inside the larger ring (leave some room between the smaller one and the ring).
Step 3: Disc 1
Cut out a circular piece of cardboard (or plastic, or whatever you have).
Aluminum Foil-Mount the foil to the disc by poking wire through each side and twisting it to secure the foil.
Conductive Ink-If you are using conductive ink, just make a thick ring around the edge of each side, maybe a centimeter thick depending on the size of your disc. Make a thick circle in the center as well. Then put a piece of wire through one side and out the other. Secure it there to make the ring on each side one conductor.
Step 4: Disc 2
Cut out another disc about the same size as the first one.
Poke a hole in the center and some around the edge.
Put the LEDs in. Put the anodes (Positive End) in the center and the cathodes (Negative Lead) in the outer holes. Twist the center leads together to make sure they all touch in the correct spots.
Twist the cathode on the other side to form a protrusion to which the spinning wire will make contact wit later.
Step 5: Base
Step 6: Motor
Next, mount two wires that will touch the foil (or ink) on the bottom of the disc on the base.
Bent them to touch the foil while the motor spins, but not so far as to have it apply too much pressure to prevent the disc from spinning. Position one to touch the outer ring and one to touch the center one.
Step 7: Wiring
Step 8: More Wiring
From the negative wire that was spliced in between the battery clip and the motor, hook up the wire touching the outer foil ring.
Step 9: LED Disc Structure Thingy
I taped the top of the disc to a crossing K'nex piece with electrical tape. Make sure it is low enough to connect to the wires that will be completing the circuit as the motor rotates.
Step 10: Finishing the thing
Position the center one to touch the Anode Lead, and the outer one to touch the Cathode leads as it spins.
Step 11: MAKE IT WORK
I will have a video up soon, hopefully. (I accidentally damaged mine and I'll record a video as soon as I fix it up)