This project started as an experiment in combining old mechanical parts with simple electronics. I wanted to build a clock that did not look like a normal digital or analog clock, but more like a piece of old workshop equipment.
The main visible parts are two pressure gauges, brass pipes and an old valve. The gauge needles are moved by 270° servos hidden behind the gauges. An Arduino Nano reads the time from a DS3231 RTC module and moves the servos to the correct positions.
The brass valve is not just decoration. I modified it and placed a rotary encoder inside, so it can be used to set the time. Two LEDs under the gauges indicate whether the clock is currently adjusting hours or minutes.
The mechanical part was the most interesting part of the build. The gauges had to be opened and modified, the servos had to be mounted behind them, and the brass pipe assembly had to be fitted to a wooden base. Some parts were not perfectly aligned on the first try, but that is part of this kind of build.
The electronics are simple:
Arduino Nano as the main controller
DS3231 RTC module for keeping time
Two 270° servos for moving the gauge needles
Rotary encoder hidden inside the valve
Two LEDs for setting indication
5 V power supply
Instead of using a simple linear conversion between time and servo angle, the program uses calibration values for the real needle positions. This makes it easier to compensate for mechanical tolerances in the gauges and servo mounting.
The result is a fully working clock that still looks mostly mechanical from the outside. From the front you mainly see brass, gauges, a valve and a wooden base. The Arduino and electronics stay hidden inside.

Details can be found on my website https://www.michaluvbrloh.cz