Although I love the Bose QuietComfort 25 headphones, I was disappointed that the otherwise-excellent case has no cable keeper. Plus, I'm a Mac/iPhone/iPad user so I needed to bring along the Apple Lightning and USB-C headphone adapters. So I designed this cable keeper to fit into the case along with the headphones.
It's designed to hold the cable reasonably well but not so tight that it stresses it. The end in particular needs some slack to leave the microphone/button widget free. Start with the right-angle plug at the base, pointing inward, wrap the cable fairly tightly toward the top, and stick the straight plug through the hole, leaving a loose loop.
The two indents at the top are sized to grab the Apple Lightning to 3.5 mm headphone adapter or USB-C to 3.5 mm headphone adapter for the iPhone or iPad. I made two spots if you have both like I do.
Bonus points if you know why I called it a "condensate".
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/hyu6QEapP1v