Summary

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.scad and sennheiser_holder.stl (this is the original STL from polxuriach) and change the size using openscad.

Print Settings

Printer Brand:

Prusa

                                            <p class="detail-setting printer"><strong>Printer: </strong>                     <div><p>Prusa Clone</p></div></p>                                                                                <p class="detail-setting rafts"><strong>Rafts: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting supports"><strong>Supports: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting resolution"><strong>Resolution: </strong>                     <div><p>0.3</p></div></p>                                                                                <p class="detail-setting infill"><strong>Infill: </strong>                     <div><p>3D honeycomb</p></div></p>                                                    <strong>Filament:</strong> sunlu PLA                black

How I Designed This

I used the original STL from polxuriach and added holes for screws using openscad.

Headphone Holder