After making small holes in my Howard Leight earmuffs (probably ABS plastic) for the wires, I notice they don't isolate quite as well as before. First I tried mixing cornstarch and clear silicone caulk to make a Sugru substitute both to plug the holes and to attach the connecting wires to the over the head piece. Although the Oogoo initially seemed to adhere, it didn't seem to block the noise out, and after a few days it started peeling away. Then I tried something I had lying around for filling in damaged wood. It isolated sound very well and was very hard, but it too came apart from the plastic. Rubber cement held about twice as good as Oogoo, but also peeled away. 

On the headband strap I also tried a combination of electrical tape and double-sidded tape, but it too peeled away from the plastic. Now I'm using plastic ties, which I later read someone else on here used and add an artsy touch, but they're uncomfortable. Anyone have any ideas?

I've attached a Sansa Clip+ to the earpiece with Velcro.