I made the prototype below, just to see if it could be done.
From a mechanical/practical point of view, it works beautifully
The strap is made from an old piece of leather I had around, and it's only a try out.
For a "real one", I need some other leather, leather DYE, and of course needle and thread to make stitches and all that.
But what do you guys think - does it look good with leather + clasp?