This corner clamping accessory is designed to make gluing corners together simple and consistent. Sized for a 1" strap, simply place this accessory at each corner of the frame you're gluing together, feed your strap through the guides of each one, and then ratchet the strap nice and tight, and your frames will be held together while the glue sets, without damaging the frame, applying a consistent pressure to each vertex, and allowing the strap to move freely around each corner.

It's recommended to use a higher strength plastic for this, as I can't guarantee how well PLA will hold up to the pressure.