Birch bark is a great material to cook with also. The Indians would fold the corners, put a peg through them, and they would have a seamless trough to cook out of, and ladle out the food. They could also sew sticks along the sides, and ends,to give it some dimensional strength, and it could be lifted off the coals. Great for cooking wild rice, musrooms, and duck! Mmmmm!
you can also use a gourd, but be sure to clean it out really well. The skin like lining is supposed to bad for the health, as is the dust. I guess you could melt some bees wax, or parafin, and coat the inside after cleaning. But I have seen pictures of gourd canteens, powder horns, shot holders, etc.
Plastic bottles? Hey, what's a little pcb's in your water, with a little chlorine, and some heavy metals......Actually a third eye could come in handy......You could check your compass, while scanning the horizon for deer......
Some of the ancients also used dried bladders, from pigs, deer, and such. The Eskimos used dried walrus bladders, to make a very light weight rain coat. They would cut, and sew them into nifty little translucent coats. I saw one in a museum in Melbourne, Fla. I had a Friend of mine, bring me back a Bota, from Spain, when I was in the Army, and stationed in Italy, that I used for some time, and finally the plastic tip started to deteriorate, and I was going to put in a wooden plug, and noticed that what I had been told was true. The Bota was made from horse hide. The hair was still on it, and on the inside! Well, I didn't use it any more. I promptly put it in the trash. I think the Apaches, used horse intestines for canteens. Same deal, scrape, and dry. Anyway, there is a host of other materials you can use. Or you could just get a big mouth full, after drinking all you can, and walk around " wit da cheeks all bowed out, eh? "
Wayne