Step 1: Materials
Drill, with multiple bit sizes
Broken Headphones, or used ones, or even perfectly good condition ones.
then all you really have to do is DRILLLLLLL, in the center.
Cut it at the bottom and VOILA!
With pliers, pull that wire out from the middle of the socket. It will make it fit better.
Cut it down to size if needed.
Put glue inside of the hole, just a drop. Quickly push the headphone in the hole!