Here is the clock in action.
and here is the what is happening behind the clock
The magnetic numbers are moved using a CoreXY style mechanism on the back of the clock.
I designed and 3d printed all of the plastic parts and off-the-shelf 8mm rods and GT2 gears. The two stepper motors are Nema 17 1.5A steppers.
The original design used an Arduino Uno controller, however during design I determined that I needed a faster processor and switched an Arduino compatible SAMD21 based controller board (RobotDyn SamD21-m0-mini). The original reason for going to a faster processor turns out was not needed, so I could probably have gone back to the Uno but just didn't bother.
The Arduino controller is connected to a KingPrint CNC Shield using A4988 Motor Drivers to drive the stepper motors and an Adafruit PCF8523 Real Time Clock to keep time.
All source code is available on GitHub