Four of these convert a motorcycle-tiedown to a strap clamp for square/rectangular objects.

I deleted the two metal hooks and stitched the long strap to the clamp. This is optional but otherwise could limit clamping of smaller items.

No supports needed while printing. Could easily be modified for gluing up awkward shapes like bestagons and octagons or triangles, by changing the internal angle. Not suitable for reflex angles, only acute and obtuse angles.