Oh wow, I've been wanting to build this for a while. But my idea was to make it wrist watch sized, and use LEDs around the ring to show the time. (Or use laser

Oh wow, I've been wanting to build this for a while. But my idea was to make it wrist watch sized, and use LEDs around the ring to show the time. (Or use laser diodes and project the watch hands on the wearer's wrist). I believe the LED option is doable but it draws quite a bit too much power, even if the LEDs aren't always on. Other, more power-efficient approaches would be using a ring-shaped LCD or e-ink display, but they do not exist off the shelf and custom orders are expensive. Or use a conventional watch mechanism to rotate acrylic rings. Anyway, I brainstormed a ton of possible ways to make this thing, but in the end, it's really hard to make small things like wrist watches.