A couple weeks ago, I was in Shenzhen, China for a hackathon and on the first day, we all used the one-day PCB fabrication to make PCB badges to wear during the event. I decided to go a little crazy and make some cool 3D alchemical-cosmological badges.
It's 3 PCB's stacked on-top of each other that's connected using testpoints on each board. The innerboard has a 10 cent CH32V003 MCU that powers the WS2812B neopixels on the outer rings using the testpoints and shines through using exposed soldermask.
If you have any questions about how the design works, feel free to let me know!