Clocks made from repurposed materials seem to be a dime a dozen in maker circles these days. But this one made by Jason Hotchkiss has quite a bit of thought and effort put into it. He replaced the platter on a hard disk drive with a copper disk, and etched in letters. It’s backlit by an array of flashing LEDs.
The disk has a white strip on the backside that passes in front of a photosensor to gauge its rotational speed. On the back of the hard drive Jason has etched and soldered an Arduino to trigger the strobing LEDs, integrated is a brushless motor controller, and he put in a digital clock to give accurate timing.
Once the clock is spun up, it gives off a lovely green hue for all your timekeeping needs.