Good question. There's only one reason: It is better than nothing.

In a "pocket" sized survival kit there really isn't room for a metal container. Traditionally, aluminum foil is included to improvise a cooking container. However, the wear and tear of carrying it around tends to cause pinhole leaks at the corners where it was folded.

This was my attempt to find something a little better for a pocket kit.

I'd never purposely go into the woods with just a pocket kit. I always bring a metal cup, among other things. But it is possible that you might end up with only what's in your pockets.

A cup of tea?

How about a Reynold's Oven Bags? They sell them in different sizes in your grocery store. If you want it even smaller, just go at it with a pair of scissors. They are food grade, and made for high temperatures. Take one, fill it with a quart of water, and then use a Sharpie marker to trace the water line (while still at home). To boil water in the field, fill to the water line mark, tie off the top, and suspend over a fire using the end of the cord/wire you tied it off with.

Another thing to consider is a foil bread mini-loaf pan. Also found in your local grocery store. They are much much heavier foil than typical aluminum foil on a roll. Fold the pan in on itself so it's flat and store in your kit. To use, simple unfold. You probably wouldn't find any holes. It may not be good for many fold/unfold operations, but fold once, unfold once is OK. And once you're in a emergency situation you'll just unfold it once and leave it that way.

Haertig has the correct on loaf pans

Never seen the oven bag thing though - if the top is sealed, wouldn't steam pressure just split the bag?

I don't believe in oven bag. There is no open flame in the oven. Anyone to try that for real?

> Why don't kit makers just give us a kit with a container that > > > opens only on one end?
Someone suggested a spectacle case for this one time. In the UK there are metal ones that open at one end. You'd have to flatten one end to stand it up as they are always rounded at each end.
They appear to be stamped together not soldered. (I was worried about lead in the solder - is this a real concern anyone?)
Any reason this won't work?
The Sock

Sock, I can't tell you for sure on the lead thing, but I always thought the big concern was developmental delays in kids with lead exposure. I couldn't tell you effects on adults. Good question.

A case that's something like 5x3x1 on the inside would hold about a cup of water. Yeah, that's not a lot, but a stainless steel container designed for kit carry would remove a lot of fussiness concerns with water in a kit. If the container is solid, and you've got means for a fire, then maybe you don't have to pack tablets or foil or what have you. It's just another approach.

Here is an option that looks promising, though I have not tried it.

That cooking pan option had been discussed many times already. Single use thing. And still prone to wear when not in use.