My Glow-in-the-Dark Plot Clock uses an Arduino Uno, two 9g servomotors, a UV LED, and a phosphorescent material to “draw” the time on demand. Whenever the button is pressed, a robot arm writes the time on the screen in glowing numerals that shine for several minutes before slowly fading away.
This project was inspired by the amazing whiteboard plot clock by Johannes Heberlein in Nuremberg, Germany , which writes the time with a dry-erase marker, and then erases it!
I really liked that clock, but I wanted a writing system that would last longer than the ink in a whiteboard marker. I decided to use a glow-in-the-dark material instead of the whiteboard, because it produces a visually appealing glow effect, “erases” itself, and can’t run out of ink. This glow effect, along with the 3D-printed enclosure, ensures that your plot clock will work reliably for years to come.
My previous iteration of this plot clock used a more expensive UV laser. Here I have replaced the UV laser with a UV LED that produces the same effect at a fraction of the cost. In fact, all the components required to build this project can be purchased for around $8 from AliExpress — that’s less than the laser cost alone. But shipping takes a long time. If you’re worried about quality and shipping time, Amazon and an official Arduino will work better.
You can download the 3D print files and Arduino code, and find all the AliExpress links there too. I also made a laser-cut version if you’ve got laser cutter access.
BUILD YOUR GLOWING PLOT CLOCK
Here’s a quick step-by-step: