After milling it is enough to cut through a hole of the desired diameter under your watch.
Or do you need to make a hole in the model in the owl?
I think it's better to drill a hole later, so that the diameter of the clock will fit.
Otherwise, you can not guess with a diameter, you work through the artkam.
I've also just glued up some English Oak to machine the dragon clock for my son this weekend, so I should be able to post some pics when done and sanded.
I'm really looking forward to doing that one, thanks again for posting the model!
It's rumoured that everytime someone buys a TB6560 based board, an engineer cries!