You should start going to headshops and ask them if maybe then can get a hold of one. I went to a headshop here in florida called "The Funky Groove" and they had this beautiful gasmask which had a hose that attached to bong at the top. All you had to do was inhale from inside the mask because it was airtight and you would be taking a hit. I didnt buy it but i should have, it was only 70 dollars. Incase you dont find any gas masks at headshops shop around online im sure you'll find one. Im not sure how i would make one.