He found a couple of high power, SMD LEDs in his parts bin. They were just slightly wider than 1.6 mm across the terminals. So he took a piece of double sided, copper clad FR4, and edge mounted ...

We’ve seen our share of light-up jewelry over the years, but for some reason — probably power — it’s almost ... this is a 3D printed ring with SMD LEDs painstakingly soldered together ...