I added holes for mounting the holder using two screws (in this case 3.9 x 30 mm sheetrock screws).
In case your screws match mine, you probably want to print headphone_holder.stl.
If you want to use screws with a different size, just download sennheiser_holder.stl and sennheiser_holder.stl
Printer brand: Prusa
Printer: Prusa Clone
Infill: 3D honeycomb