I have always wondered why no one has ever made a pouch out of kydex that could be bolted on to a sheath, at least I haven't seen one, and I have seen everything.
I also don't think there's a law that says a pouch has to be made of nylon, leather, or canvas.
I think it would be cheaper to make and better than nylon. I mean if I'm trusting it to hold a knife, it better be able to hold a few survival items.
You could even make the kydex in different sizes or even the full length of the sheath and maybe 1'' thick to keep a lower profile but still have room to store things in. Then just make a simple nylon flap to close it up.
If they can injection mold two halves of a sheath, why not have one more mold for the pouch as well, but this time make it 1.5'' deep or something??
Now if you really wanted to be Johnny high speed, have it punched out of stainless steel and a little thicker than what the Altoids tins are. Then you could use it to boil water in as well. The only thing is, you would not have a flap and buckle to get into it because you would need a 1.5'' wall all the way around it to hold water. To get the the items you would need to unscrew it, but if you are doing that, then you are down to your last ditch survival items anyway to my way of thinking.
If it was 6'' long and 2'' wide and 1.75'' deep, it would boil 11.6 ounces of water for an example For me, water, and a lot of clean water is the hardest thing to make sure you have when you are talking a smaller kit. It would weigh about 3-4 ounces and hold the same amount of gear as about 3.5 Altoids tins. A cup is really the hardest thing to make in the bush and worth is weight to have as far as I'm concerned.
Of course this would mean you would need to redesign the sheath and make it a rectangle, but if it's worth it????? That's something the number crunchers would have to decide.
Now you could buy a kydex pouch with flap that could be a lot cheaper than a nylon pouch, or you could buy the SS one and have your pouch doing two things, storing survival items and boiling water.