A small corner clamp for joining pieces up to 15mm in thickness.
It requires two M5x50mm screws and two M3x4mm set screws on the thumbwheels. Alternatively the jaws can be tightened with an Allen key from the inside of the corner angle.
The end of the screw needs to be flattened so that the setscrew can fix the thumbwheel, the hole for the setscrew needs to be tapped, or alternatively the thumbwheel can be glued in place.
It may be necessary to drill the holes for the screws to 5 or 5.5 mm to make things run more smoothly.
I printed mine at 0.25 layer height, 4 perimeters and top/bottom layers with 15% honeycomb infill.