I am trying to come up with a custom water/meth kit. i have approx 20 inches in length and by 3.5 inches in diameter (cylinder shaped). Exhaust pipe fits the bill but I am not sure if it would rust. Stainless steel or not over time I would think it would crap out if there was meth in it.

i thought of plastic like plumbing tube but it will be kinda close to the exhaust so it might melt.

Any ideas guys?