So refitting defunct watches has become a hobby for him, and this example is a doozy. It uses an Enigma emulator running on an Arduino ... A small OLED screen peeks through the front bezel ...

If you’ve got an Arduino, a few passive components, and a SSD1306 OLED, then [mircemk] might have the answer for you. As you can see in the video below, his code turns a handful of cheap parts ...