Two pressure gauges and a plumbing valve, and that’s a fine way to hide a microcontroller.
This is Michal’s Steampunk Gauge Clock, and the dials are the clever part. An hour needle that sweeps a 0 to 24 scale is a stranger and better idea than another twelve-hour face, and a needle like that has a reason to be there. Michal says the aim was this:
the outside as mechanical and old-looking as possible, while hiding the electronics inside.
270° across 24 hours is 11.25° an hour, so the hour needle moves just under a degree every five minutes, and I’d guess a servo’s slop shows up fast at that scale. Michal’s page says the software uses measured calibration values for the real needle positions rather than a straight time-to-angle formula, which is how an engineer fixes a gauge face that was never meant to be a clock.
Then the valve. You set the time by turning the valve’s handwheel, with a rotary encoder hidden inside the valve. Why wouldn’t a man hide a knob in the one part everybody already wants to turn? I would, and I’d do it the same way.
Can I build one? Not from the Hackaday.io page, where the files, logs and instructions all sit at zero. Michal’s own site is linked there, and that’s where I’d go for the wiring. The base is a plain dark wooden box that I’d swap for something with a drawer.