A space invader wall clock.
Works with those kind of clock mechanism : https://www.amazon.com/YIWULA-Quartz-Movement-Mechanism-Repair/dp/B01N8WNWOB/ref=sr_1_1 or any other that has a shaft diameter of 7mm.
I also advice you to take a silent one, I personally hate the "tic tac" sound of the clocks.
The shaft is a tight fit, I actually ended up tapping the center hole, that works just great !
The design is quite small but I made it so it fits my Tevo Tarantula bed without any issue.