Bestest shoulder strap buckle

We had a broken adjustment buckle for the strap of a messenger bag. This was designed in FreeCAD as a replacement, and I think it is very proud to be doing the best buckle job in the world by the looks of it. Print this with 100% infill for strength - it is 6mm thick, and feels like it can do its job (at least if you ask the buckle :-)) but of course use your own judgement if you have a heavy laptop bag for example. This fits a 40mm wide strap. You might be able to scale it accordingly to fit different sizes. Thanks to the cutout you can insert it into the strap without sewing. And maybe print a few with different colors just for decoration?