You need a zipper that matches the lenghth of the headphones and some sewing thread.
Starting with one side of the headset, fold the fabric in half and sew it when the earphone is inside.
Sew the entire lenghth, when you are done it should be like the picture.
Do the same with the other side of the headphones.
When you're done it should look like this. When its closed its really comfortable and the headphones will not tangle.
To use the headphones just open the zipper.
Enjoy my other guides and follow me!