I dont know exactly what you are looking for, but I have got a small clock that is designed to be recessed into wood etc.
I bought it from a local supplier which sells clock modules, parts and hands etc so you can make your own clocks.
The clock I have is about 22mm and I've seen people use them in paper weights and pen holders for desks. (I got it for an unfinished project)
I hope this helps you narrow down your search.