“A Clock Projector can project the time to a ceiling in the night.
There are lots of commercial alarm clocks with integrated clock projector on the market but I thought, it would be fun to build one myself.
Moreover it was a good project for becoming accustomed to the process of 3d-designing cases which can be 3d printed and to learn about designing tolerances.
The principle is easy – basically it works like a video beamer (or any other projecting clock^^).”