Josh wrote an answer about Black Diamond AvaLung II on November 11, 2010
I was worried about the mask getting ripped off at first.
However, I'm more worried that the mouth piece would get ripped out while I was biting or my bite would loosen in an avalanche. Also if you become unconscious your Avalung is useless.
I'm confident I can construct a mask that will stay on my face.
I think the hardest part is going to be getting the hose to stay connected to the mask.
Anyone have a beater Avalung they'd sell for cheap so I can make a prototype?