I have S-hooks to hang a few things overhead, but needed a way to keep them from unhooking without bending the hook closed myself. This slips on to the end of the hook and rotates into the middle portion, snapping into place and will not be pushed off.

This is for a 1/8" (3mm) S-Hook, but may make other sizes down the road.

Any layer height will do, I used PLA but any type will do.

March 30, 2022:

Added the F3D file for custom sizes. Please excuse the poor design, feel free to reach out to explain anything you need.