This headphone hanger can be attached under a desk.

I printed it in PLA at 0.2 and 15% infill with no support and its solid. It just needs four screws appropriate for the desk you're attaching it to.

Print instructions

Category: 3D Printing Print Settings

Printer Brand: Creality

Printer: Ender 3

Supports: No

Resolution: 0.2

Infill: 15