You have to be a genius to think this through:
The sundial displays time (with actual digits !!) from 10:00 until 16:00, updating every 20 minutes. You can precisely adjust the displayed time simply by rotating the gnomon (the magic box that displays time). So you can even adjust for Daylight Saving Time.
Found on reddit sub r/mildlyinteresting
Details about the process and files to print it yourself are here:
… and it is a thing on wikipedia