Moose408 on instructables shared this cool clock. It features the Adafruit PCF8523 Real Time Clock Assembled Breakout Board.

I enjoy designing and building interesting clocks and am always looking at unique ways to display the time. This clock uses 4 vertical slides that contain the numbers. Four stepper motors position the slides so that correct time is shown in the display area of the clock.

The steppers are controlled using an Arduino Uno with a CNC Shield. It uses an Adafruit PCF8523 RTC board to keep the time. The case and mechanical aspects are all 3D printed and the slides displaying the numbers are made of wood with laser engraved numbers.

I used 3d printed rack and pinion gears mounted on the back of the wood slides to move the slides up and down. The rack and pinion system was derived from this linear motion device made by Trigubovich on Thingiverse.

If you’re looking to make a new way to keep track of time, read more about the project here.