http://www.approvedgasmasks.com/images/msaMCP1.jpg This is the gas mask i have, its a legit military gas mask. i really want to hook it up to something but im not exactly sure on how to do it. i would guess cork some of the holes and get some kind of rubber seal to hook a piece up to it. im not sure if it would work though because first of all these gas masks dont have a back, and 2nd, if you look through the center, you can see where your nose goes, that pretty much seals off your mouth and noes from the rest of your face
Hmm, it's sort of hard to throw out suggestions when I don't know where the air is brought in. To seal of the areas you don't want air coming through I would maybe try hot glue? I don't know haha I thought I would have better ideas but i just can't think right now. Good luck though it would be sweet if you did make something.