I'm planning to build a PSK, but not sure what container to use for it. It's not a pocket version, but something I can throw into my pack when I think I may need it.

The current options are Otter box, tupperware, 1L SS water bottle, an old SS lunchbox I have, and nylon bag.

Otterbox is very strong and waterproof, but the box itself takes up a lot of space, and there aren't much space inside a 2000.

Tupperware is waterproof and relatively compact.

A stainless water bottle would be strong and waterproof, and can be used as snow melter and water boiler if needed, but content inside would be hard to access, and the shape would be hard to carry.

The old stainless lunchbox I have is not waterproof, but can boil water, and easier to carry and access than a water bottle.

A nylon bag like this or this would be easiest to carry, to fit things inside and access them, but of course they aren't waterproof, or used as water container.

So any thoughts/suggestions?