Made myself a hook since I bought a pair of headphones.

The mounting idea came from:
https://www.printables.com/model/522929-ikea-ivar-hook-snap-on

The idea of using a stiffener came from:
https://www.printables.com/model/835692-ivar-hook

The actual stiffener design is made from free-hand B-spline curves, nothing special.
A step file is attached in case you want to edit yourself.