The LED lights are something special I had made from Fiber Optic Products Inc. Usually they consist of 2 LEDs, one of each color. R2's front PSI is red/blue, his rear one is yellow/green. I noticed that it wasn't quite bright enough for my liking, so I asked him to add another LED of each color. The LEDs are very focused. So if you just point them forward, you'd be staring at a small colored dot.
Keith at ResinParts.Com offers a nice PSI Flasher Kit. That's what these white pieces are, essentially the "cup" and "cap". Made of white, highly reflective resin (or just ordinary white resin for all I know), it already has a raised surface for the PSI Board to attached to and a cut out groove for the wire to escape from behind.
Here we've hot-glued the PSI light board to the flasher cap...
Now here's the view inside the cap. The "flanges" at the top are what you would attach to R2's dome. As you can see, the LEDs are pointing to the side walls, so that the flasher fills with light.
Pardon my lousy camera but now you can see the green LEDs lit up. See how focused and bright the light emitted is on the right side?
Now, with the filter/lense cover. This is simply a "milkplex" material, the same stuff they use to view X-Ray films. Notice how the entire lense is full of light. I found with only one LED per color, the fill wasn't as strong. It takes a fair amount of tweaking and very gentle bending of the LEDs to get the perfect lighting.