If you have a mechanical clock, put a single LED on the end of each dial, mount some frosted glass or plastic plate a few cm in front of the clock face, and glu

If you have a mechanical clock, put a single LED on the end of each dial, mount some frosted glass or plastic plate a few cm in front of the clock face, and glue a pole in the center of the plate between it and the clock face to make the LEDs cast shadows on the plate. Easy, except for reliably powering the LEDs.