DIY Gas Mask With A 2 Liter Soda Bottle - Commercial gas masks are very expensive. While I DON'T believe this DIY gas mask provides the same level of protection, it is a great alternative that will protect from particulates, including tear-gas, if you cannot afford a commercial mask, or you are in an emergency survival situation.This soda bottle gas mask is very cheap & very easy to make. You could make one in 5 minutes. All you need is a two liter bottle, duct tape and a n95 rated face mask.