Take an etchasketch. Add three servo motors controlled by some software.

Servo 1 wipes the screen.

Servo 2 and 3 controls the x and y axis to draw the time.

Every 58 seconds servo 1 wipes the screen and servo 2 and 3 re-writes the time.

Brilliant

Etchasketch PLUS

It integrates into your calendar via wifi and also draws your upcoming calendar appointments

Even more brilliant