This pingpong wall clock would light up any wall! Via Hackster.io:
Makers have long known that ping pong balls make great diffusers for LEDs, but now, using individual RGB LED PCBs, Tjjensma has taken things to a whole new level and created ping pong ball clock. This device, which uses an Arduino Nano clone and an RTC module for accurate timekeeping, involved daisy-chaining well over 100 LED modules together to form the display.
The clock itself — meant to hang on a wall — looks like a sort of stretched-out hexagon, with sloping side pieces and a long middle to display hours and minutes, along with a colon to separate everything. Woodworking involved is simple, though effective. Wiring seems fairly straightforward, but actually soldering all the LEDs together had to be quite a bit of work
You can see a video of the clock in action on reddit
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