This Etch a Sketch Clock is a great use of an old toy!
“I use an Arduino driving two very cheap darlington stepper drivers with 64:1 internally reduced steppers for the drawing. For the rotation I’m using an Easy-Driver driving a Nema 17 stepper.
I also have a DS1307RTC real time clock installed so it always knows the time. Setting the time is a one-off via USB connected to a PC. Once done, you un-tether, and then the RTC keeps the time, for up to a year on the rechargeable battery, or so I’m told…”