Photochromic Clock

Clock that glow in the dark

Screenshots

Hunter's comment

The product employs an array of UV LEDs that illuminate a photochromic face while the part of the glowing screen, the material shines at first with response to the LEDs and then it stays ‘on’ after they turn off, showing four numbers.

Link

https://www.instructables.com/id/Photochromic-Glow-in-the-Dark-Clock/