This is a webbing slider for adjusting the point of contact between webbings and textile goods. Can be used to tighten or loosen straps.

I've included STLs for two sizes/styles listed in millimeters, webbing width followed by webbing thickness. These STLs all have 5 mm thick arms. The OpenSCAD file is fully parametric, and can be used to create STLs for any width and thickness of webbing, or thickness of hook, by adjusting the fields in the customizer.

Its strength will be determined by your print settings and material, but the design itself is surprisingly sturdy.