Okay yeah I think I could make this in a wall clock and it wouldn’t be crazy. I need to talk to my grandpa–he does clockmaking and repair as a hobby–but I think that if you made the rotating light-blocking layer out of something lightweight (plastic or paper, maybe) you could probably rotate it using a high-torque clock movement, attaching the light-blocking layer where the second hand would go. If you used black paper for that layer, you’d have to perforate it a lot to let light through. A thin but sturdy plastic would probably be better; you could block light with black paint and also scatter some bits of alcohol ink so stars occasionally shine red, blue, or yellow.
The top layer you could just do as a print on heavy paper, using whatever star map you wanted, and then cut or puncture the stars out–leather punches would be easiest. Attach that to the glass face of the wall clock, covering everything inside. Then, the inside of the clock–where the face used to be–would need a reflective coating (spraypaint or aluminum tape, maybe) and LED strip lights around the edge so that there’s light shining through the perforations..
You’d need power for the LED strips, but the clock movement would probably be battery powered.
So now I just have to keep an eye out for a good wall clock.
I wound up using foamcore and matboard, and a rotating display pedestal instead of a clock movement, given the scale, but that does make the whole thing powered by USB.
