This is what I have so far:
This shows the large salvaged fan and my slip rings. I made these from two plastic draw knobs that had flat faces and with a hub that happened to fit snugly into a short length of electrical conduit. The cylindrical contacts are hard copper plumbing pipe with wires soldered to them and passing up the centre of the conduit and on to the MDF disk. The two springs are DIY and made by simply winding steel wire onto a length of allthread.
The slip ring assembly connects disk to the fan hub with silicone sealant.
This shows the electronics that drive the LEDs, phototransistor and IR decoder. The transistors drive the LEDs and the arduino pins drive the transistors. This all seems to work well and now it is just a matter of getting the programming right.
I have used curtain weights to balance the disk
Another MDF disk with 26 3mm LEDs screws down on top and with a plug that goes into that IDE type connector.