Well I'll tell ya, I have tried a lot of carry methods. I have tried various tins in a multitude of shapes and sizes both with and without watertight seals. I have also tried the AMK zipper pouches like the one Doug's prefab PSK comes in. I have also tried small waterproof key FOB spy capsule tubes, a carabineer with everything dangling off of it, small belt pouches, sparklite boxes, dental floss boxes, the Tad Gear Life Capsule and even a Zippo lighter with the "guts" removed. Until recently I was carrying everything in and Eagle Creek nylon zipper wallet.
As far as something that is waterproof AND you can boil water in it without destroying its waterproofing, the only one that would work from my long list is the Tadgear Life Capsule (with the o-rings removed). I think Tadgear sells them for $28 with their fake paracord Lanyard. If you really want one I'd sell you mine which is in mint condition, for $20 and even stick a REAL 7 strand paracord lanyard on it... heheheh. It pretty much just sits on the shelf. I tried it and found that I needed something bigger. It's probably going to be on ebay soon. Once I'm positive that I don't have another use for it. <img src="/images/graemlins/smile.gif" alt="" />
Right now I am carrying all my gear in a Spec Ops wallet (the junior version). All my gear goes nicely hidden away in the two zipper pockets and my normal wallet EDC stuff like ID, credit cards, cash, etc go in the exposed, non-hidden, non-zippered pockets. I like having my PSK integrated in to my wallet because I am a very firm believer in having it with me 24/7/365! Is my Spec Ops wallet waterproof...nope. Do I care?... nope. Why don't I care? All of my gear is waterproof. In other words, why care if my container (the wallet) is waterproof when every single thing in it is waterproof? As far boiling water goes. I carry an ample supply of water purification tabs. If I need to boil water for other reasons like sterilizing a knife or scalpel blade, then I have my heavy duty aluminum foil.
I'm always on the lookout for a better carry method but I haven't found one recently.
There's my two pesos.
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Learn to improvise everything.