Headphone holder 80x60x20. Connected at pipe clamp with M8 lock bold.

V2 is without tabs. V3 is with tabs, so headphone does not slide off. This holder is wide enough to hold two headphones (depending on headphones).

Hexigon hole has diameter of 13mm and should fit on pipe clamp nut, so it does not rotate around bold. Before printing, look if rotation of pipe clamp nut is correct. Different brands of pipe clamps have other rotations. The cheap clamps are even at an angle. Mine had the flat spot at the top. Used bold is M8x60 lock bold as seen on picture, but other bolds can be used that fit the 10mm hole.