Is this good for a stem+bowl?

make sure peice b is pure metal, no plastic or rubber on it, if it has either this won't work. you need electrical tape (it's the best tape for bongs, do not use the rubber cement because it would give off vapors when the peice got hot)

ok tape part b to end b, but keeping the tape farthest away from the top as possible. give it a few times around and that should be good. then cut about 1/4 of the hose, and part a off, and discard it.

next get an empty 1 liter (2 liter would work, but 1 liter would be optimal, for performance.) about half way down the side put a slit in the bottle, a very small one, you want the hole just big enough for you to stick that tubing through, take your time and do it as cleanly as possible, scissors would make it easier after making a puncture with a steak knife or something.

feed the tube in, so that a little less than an inch is left outside the bottle, and put a good bit of rubber cement just where the bottle and the tube meet on the outside, then on the silver part that goes around the tupe on end b, put electrical tape around that, going around the bottle as well, but keeping the bowl angled so you won't burn the bottle trying to light the bowl. let that all dry and rest, then either with a knife and a pair of sissors cut a small hole near the top (for a carb) or you can use a cigarette butt, to burn it through.

when the cement is dry all you have to do is to fill the bottle with just enough water to cover the bottom of the tube by about 3/4 of an inch (maybe 1/2 inch), then put a little bit of weed in peice a which is your bowl put your finger over the whole in the top of the liter hit, and when your lungs are almost full you breathe in hard but move your finger from the hole at the top.