Well, they do some. They're welding goggles. I got them to experiment with and find the best way to make a comfortable strap. Here's one solution I'm happy with: EPDM Rubber with maille (in this case, flattened steel. I've also used brass) in an E6-in-1 pattern. And it's removable! Not sure yet what to charge for this, but I'd like to be able to do custom orders for a fairly consistent price - with slight differences for materials.
Click on the pic for a close-up of where the strap attaches to the goggles.