This a tutorial on how to make a Redneck Special Ops gas mask. It has changeable filters, and you can change the type filter for your operation.
Step 1: Materials
you will need 2 bottles, a knife, duct tape, hose/tubing, respirator, and rubber bands.
There are many sizes of bottles. You will want to pick a bottle with little grooves and little bumps, to minimize distortion. Perhaps a 1.5 liter or bigger, but not too big!