I want to make my own stuff bags and there are a few features I want it to have. In order to make them I need help finding gear and som ideas.

-Made out of silnylon or similar (waterproof).
-Roll top closure like sea to summit bags


I've seen bags with air valves that lets the air out the bottom of the sack when you roll the top down. Then the valve is closed and you have a very compressed stuff sack.

My first idea was to make a "schnozzle" and skip the valve but then I saw the exped schnozzel pump bag and realized I want something like that so now the wishlist is:

-roll top closure
-able to pump my exped mats
-able to let air out but not in when closed.

Does anyone know where I can find valves to put in my bags. Preferably but not necessarily like the ones used on exped mats.
I've looked around a little but so far I've mostly found poor quality stuff made for childrens swimming toys.

Looking forward to hear your ideas.