This clip is intended for the hanging of pictures or other items from a picture rail that can be found at the top of a wall in older homes that have plaster walls, where marring the hard and brittle walls is a problem.  Simply slip the clip over the round feature of the picture rail, tie on your string or wire of choice through the small hole, and run it down to the hangers on your picture frame.

Simulated with PLA material properties and should support approximately 1kg (2.2 pounds) per clip.  The weak point is at the top of the hook - I had to thin this down as my picture rails are closer than they should be to the ceiling.

More versions is coming that will support more weight and include hooks for affixing string lights.