I've always wanted one of those flashflight discs; you know, the ones that light up so you can play at night. unfortunately, I really don't like the weighting of them; I can't for the life of me throw a flick with it, and they're a bit expensive. so I decided that I'd make an attachment for my current discraft ultra star that does a similar thing. it's removable, and the only modification you make to the disc is a small hole, which shouldn't make any difference to the aerodynamics. (you could glue a nut to the bottom of the disc, but it wouldn't be as secure.)
Step 1: Get stuff and things
a soldering iron
a CR2016 (or similar) coin cell
a small bolt with corresponding nut
plastic (not pictured)
hot glue (not pictured)
hacksaw (not pictured)
Step 2: Solder LEDs to perfboard
solder the LEDs as shown. make sure they're near the edge, and bend them to a 90 degree angle.
Step 3: Drill hole in board
this step probably should've preceded the soldering, but regardless, you need a hole in the board that's roughly the same diameter as the bolt. make it as centered as possible (I didn't do very good at this part).
Step 4: Tin the bolt head
the bolt is going to become the positive contact for the battery. as such, it needs stuff soldered to it. however, it's pretty hard to get solder to stick to a bolt with a soldering iron. a torch does it nicely, though, so we will coat the entire head of the bolt with solder so we can use the soldering iron to solder wires to it later. make sure to use plenty of flux.
Step 5: Solder bolt into the board
now that the bolt is coated in solder, we can use the soldering iron to connect it to the board. first, solder as much of the bolt as you can to the contacts on the board to lock it in place. after that, solder all the positive leads from the LEDs to the bolt head.
Step 6: Attach plastic shielding
next, we'll attach a plastic ring to separate the positive leads from the negative. cut a piece of plastic (I used an old credit card) to the shape shown, and hot glue it into place (as shown). then spread a bit of glue into the crevices to secure it even more.
Step 7: Create battery holder
this part could've been done better, and I may revisit it. but for the time being, I've bent the negative leads into the shape shown to hold the battery, and soldered the whole thing in place. you may need to do some creative bending to get the battery to make secure contact with both leads.
Step 8: Cut bolt and affix to disc
lastly, cut the bolt to an acceptable length so that it won't be preposterously long, but will still secure the device to the frisbee. make sure when you cut the bolt you put the nut on first, so the threads can realign as you unscrew the bolt. then, drill a hole as close to the center of the frisbee as possible, and put the bolt through it, securing it with the nut.
the LEDs cast light out from the center, which both puts light in the center and on the edge. the plastic is somewhat translucent, so the light makes it through the disc and illuminates it from the inside out. it's pretty bright in the dark, and the difference in weight isn't too noticeable.