Back when i was younger i made a 'hooter', thats what we called it anyways. I was easy to make and was pretty cool. I had a half mask resperator, i took the filters off and replaced them with bottle caps. The caps kinda screwed on but were not a perfect fit, so i also used some 2 part apoxy to help hold the caps on. I made a hole in each cap for the hoses to attatch to the mask and with grommets and the right size holes the hoses fit into the caps for a nice air tight fit. I Y'd the 2 hoses into 1 slightly larger hose and thats basically it. You can attatch the hose to a hookah and put the mask on, or put a joint in the end of the hose, or whatever.. i wish i had i picture. If you don't modify the exhast on the mask you will be able to just strap it on and breath. I might have to make another 1 some day.