A friend Disneyland trip was coming up and we had the idea to make little light-up pins for the whole group. There’s a small PCB, 3D printed border in custom colours and then the whole thing potted in tinted resin to provide some diffusion. They will last about 100hrs on a single CR2032 which is plenty for a weekend trip.
A small STM32G031 powers a 4×4 matrix, there’s a 3V boost to keep the led brightness consistent over battery discharge and an ALS so we don’t blind everyone while inside but also makes them daylight visible.
Fred Temperton 