I made a simple pin badge for the Noisebridge hackerspace in San Francisco, which simply blinks old-fashioned through hole LEDs.

I used 1.6mm substrate for a lightweight design.

A deeply confounding problem I encountered with this badge was that it turned out that I had some infrared LEDs mixed in with my “red” LEDs. This initially baffling problem was eventually discovered by noticing the dyes of the LEDs were different. The lower forward voltage of the infrared LEDs made any visible red LEDs non-functional at the same time.