This is a remix of my previous remix of laird's watch strap and Lindsay Fowler's buckle. I added a latch and I used a piece of 1.75mm filament for the pin on the buckle.
I have clipped my 20mm wide strap to 10mm. It's still 1mm thin.
I refer to my previous 20mm version for printing suggestions. The pictures show the strap being printed at .10 mm layer height and clearly having some calibration issues. I presume the result would be better had I printed at the coarsest possible quality as long as the filament loops around the pinholes.
See here: https://www.thingiverse.com/thing:2867440
Update 13.10.18: Added the split version of the buckle. I prefer printing this wat and glueing with superglue afterwards. On my previous watch strap this has now held up for 6 months daily use.
This is a ladies watch and to be honest the long strap is too long and will either have to be cut to fit the eventual wearer or cut in software and reprinted.
I have printed the ring in pla mainly out of curiosity to see how it will hold up to wear.
I have now worn the 20mm version for 6 months daily and it still works fine and is strong.