I used to make flat tinder packets by putting cotton in between two sheets of lamination plastic, then laminating it together. It's waterproof until you need it, at which point you cut the laminate to expose the cotton fibers. The whole thing will light and burn quite readily, no need to remove the cotton from the plastic (just try not to breath in the smoke).

I used to keep two credit card size packets in my wallet, but I've since used them and haven't had the chance to make more.