I started by selecting the movement that I wanted to use - the ETA 6497. I then looked up the movement dimensions. This movement is 36.6mm.
I then looked for cases designed to fit a 6497. This is a pretty large movement (originally meant for pocket watches) and I wanted the smallest case possible. I eventually landed on a 42mm case from SK-watchparts.
Different cases require different dial diameters. This one needs something the same size as the movement or very slightly larger. I went looking for something between 36.6 and 37mm. It needs to be designed for the specific movement so that the dial feet are in the correct location.
Similarly, I looked up the dimensions nedded for the hands. The case opening is 34mm so I went with a 17mm minute hand so that it barely clears. A 15mm hand would probably look better tbh. The hands have different mounting diameters so I made sure to get ones that were listed as fitting my movement.
I’m planning on trying to make my own dial next - I want to use a piece of reclaimed wood with a markings engraved and filled with coloured epoxy.
Yea, that comes next ;)