Rafael Riber created a retro watch with HP QDSP-6064 Bubble display like 1970’s HP calculators:
RetroWatch
The display is controlled by an Atmel ATMega328P-AU MCU with Arduino code, and the time is kept by a Maxim DS3231 Real-Time Clock module, that stays connected to the LiPo battery at all times, keeping time even when the microcontroller and display are not powered.
RafaelRiber shared the board on OSH Park:
OSH Park 