A digital clock that uses sliding frames to conceal certain segments of the digits.
Every minute, the frames move in a synchronized manner to display the current time.
The clock is powered by a microprocessor that controls eight small stepper motors. A battery-backed real-time clock (RTC) module keeps track of the time.
(And no, it’s not nearly as loud in reality. I failed to adjust the sound level when I tried to use noise reduction to eliminate the background noise from the recording.)
Build one yourself: