Greenhouse hook

A quick print fully functional no-moving-parts hook for aluminium greenhouse rafters.
Slots into the gap in the aluminium rod and a 90 degrees twist locks it in place.

This is version 2, more robust that version 1 that had springs on the shoulders.

I designed it in openSCAD, fully parameterised so if anyone wants a slightly different size, slope on shoulders etc then let me know. It's easy enough to do.