R. Stern writes:
I made my boyfriend a reusable lunch bag out of a FedEx Tyvek mailing envelope. I modeled it after a paper lunch sack. To keep glue away from our food, I used a sewing machine to do up the seams. Because Tyvek is tear-resistant, the stitches should hold it for many lunches. It should make a great water resistant, reusable alternative to the paper sack. I don’t expect it to last forever, just until I find another free Tyvek envelope.
See R.Stern’s reusable lunch bag here. – Link.