This is a project i have been working on for a little while with the goal to retrofit a popular timepiece (casio F-91W) in to a printed case.
The body can be printed from any type of filament. I used Rosewood Timberfill from Fillamentum for this watch.
The strap is best printed from a very soft material like FFF World's FlexiSmart. Tougher flex materials make for an uncomfortable plasticey-feel fit.
The glass is 27mm in diameter and 2mm thick.
Print the buttons and strap with a flex material.
The glass should be friction fit, but as we're working with very tiny margins, what has worked for me on my printer, might not translate to another machine.
Use support everywhere. 10/15%.
Clear watch in the picture was a first revision.
Best of luck!