Stupid idea: shove a bottom mount led in sideways. who wants to take bets on whether this will work in OSHpark's smallest drill size swiss cheese!
These are .26" circles. They are rather small to be used for buttons on a button down shirt, but could be for shirt collars or other very small buttons.
Buttons. Just clothing buttons. I made two different designs, the first of which should arrive back from fab in a few days.