I found some Headphone Hangers I liked but none of them were done in OpenSCAD. This one is, and is slightly parametric. You can easily adjust the length of the object and the size of the mounting holes. (If you change the length remember to take into account the full depth of your headphones, not just the band that goes on your head, otherwise they'll hang at an angle against the wall.)
More about this project: https://rasterweb.net/raster/2023/02/12/headphone-hanger-in-openscad/
The author marked this model as their own original creation.