During World War II, the Enigma machine helped the Axis powers send encrypted messages. While these messages were eventually able to be decrypted by the Allies, these suitcase-sized devices were nonetheless an electromechanical marvel of the time. Fast forward nearly 80 years from their heyday, and hacker “asciimation” has distilled this encryption device down to a unit that can be worn on your wrist, and with this project the same guts (or nearly so) have been stuffed into the case of antique pocket watch.
He had previously modded one of these watches with an entire MP3 player device in it, and decided to apply this kind of miniaturization to Enigma circuitry. After considering using a bare Microchip chip to power the device, he eventually settled on an Arduino Pro Micro to power the it. As with his wristwatch build, a series of buttons allow for settings selection and letter input.
The actual watch used is a half-hunter style, meaning that it open with the press of a button on top to reveal the internals. To go along with this pop-open feature, a plunger switch is used so that the Enigma boots up automatically when the lid is opened. Be sure to check it out in the video below, as he shows off how it works and is assembled: