My wife wanted to fill a big portion of white wall we have above the TV, however we didn't want to drill holes or anything to support shelves securely, for example. We have paintings on other walls so this was out of question as well.
She suggested about a clock and then I suggested to print it, and print it big!
I started looking for inspirations online and settled down with the idea of basically scaling up a nice looking wrist watch face.

Outer diameter is 80cm.

Each hour marker was double-sided taped on the wall, as well as the hanger for the center piece.
It is only needed a clock motor, that you can buy anywhere, and probably adjust the size of the holes on the hour and minute hands for a snug fit on the real life clock motor.

Source file attached!