Fortuitously, for my birthday I got a make-your-own wind-up clock kit, so I used that. Here's the result:
I can't hang it on the wall, can't easily read it and the longest it has run before stopping is seven minutes. I could fix these issues by standing it on my desk, painting the numbers on it in black and adjusting the base so it's absolutely horizontal.
What I can't fix is the fact that its ticking is so loud it would feature in every Zoom call I made and probably keep me awake at night from ten metres away. That's if I wasn't distracted by it to the point of dismantling it.
Maybe I'll set it up in my office at work and use it to frighten students.