Considering the latest redesign idea, I'm not aiming at a very small pendant with just the microcontroller, connected to the #Electronic Barrette Hub for power. The hub will also be used for programming the display over the USB, this way I can use a very small and nice-looking connector on it, which won't interfere with the eventual resin casting.

That means that the PCB design will be greatly simplified, but I have to wait for it until the design of connectors for the barrette is finalized.