Small housing to hold the 3.5mm female jack to make my Audio Technica ATH-M50s' cable removable. Housing is just superglued to the headphones.
I used these audio jacks from amazon, but there are many similar ones that should work (mine had an outer diameter of 8mm and a length of 16mm from tip to end of the black part).
This is used so that I don't have to cut into my inner headphone housing to fit the jack, as is done in this instructable..
I printed in Amazon PETG at 0.2mm. Could be easily done at lower height for more finished look.