Since you're going to have to wire things to the board for the light portion of the optics, doesn't it just make sense to skip the fiber part and just use one LED per button? Sounds a lot less messy to me.

I now have a couple of extra sets of buttons (thanks David!) so I'll probably try putting in some LEDs in the near future (same small ones that people like swapping into their Nokia phones, etc.. Just have to make sure I get ones rated for the proper power.)

Bruno