For those with an interest in Arduino or timekeeping projects, YouTuber mybadpc posted a project-in-progress right up that alley: a 3D-printed mechanical seven-segment clock. Each of the four seven-segment digits is controlled via a single stepper motor to display zero through nine. The stepper motors are in turn controlled by drivers powered by an Arduino Uno.
All of the parts for the clock, other than motors and Arduino, were designed in Fusion 360 and printed in PLA on the Ender 3. The four motors utilized are NEMA 17 stepper motors, controlled by A4988 stepper drivers. The mybadpc Youtube channel currently has three separate videos documenting the work in progress, including a proof of concept not yet using all the printed parts and a more recent demonstration that includes the final parts.
Even in the more recent video, the device shown is definitely unfinished — down to rubber bands and toothpicks holding things together. Still, it demonstrates the stepper motor's ability to shift the printed segments, with satisfying, although maybe a bit loud for a bedroom clock sound effects. While this demonstration has the display showing manually entered numbers, the finished clock will display time as kept by a DS3231 RTC module. If you’re interested in following the project, expect updates to the YouTube channel — the designer is welcoming feedback and questions, so it’s a good time to get involved.