long-neck, round bottom flask is a must. for many reasons.
don't fuck with anything else. spheres have awesome compressive strength against air pushing on them from outside; not much from inside. the long neck minimizes the disturbance of that strength, gives some room to attach a bag without getting in the oil bath; gives a way of clamping it stable, and more.
the sphere will recirculate gasses and vapors; they don't want to go up the neck, except for beeing under pressure, as when the gasses in the flask are first warmed up.
check this out:
first time swim attempted to vaporize a bit of meth, and knew nothing about it , he dropped a pinch in the bottom of the rb flask and proceeded to heat it gently with propane. i assumed i would simply take it in from the flask neck when it emerged as vapor. well, it vaporized all right, but since i hadn't kept the top sealed while i was heating it, the air in the flask was able to expand without pressure as it heated.
when swim saw the melting beegin, he put the thumb over it.
and the dang vapor just stayed down there, in the sphere, twirling gently; ignoring the escape hole and swims lungs.
har-har. swim even put a straw down the neck to suck those fumwes out, but all he could do was suck in new air from above, and the meth vapors just stayed in there.
(swim let it cool and poured some water in and ended up drinking it)
so that told me something. try it. its sorta funny.
the HI does the same dance if its not beeing squeezed in a small space.
btw, what's a good temp? gradual climb from cold, to as near the boiling point of water as you can go, comfortably.
last item:
swim doesn't inhale stims, but he was challanged by some couch-fries to come up with a way to not waste the exhalation goods. and he did. but he never described it to anyone.
so i'll do it now, beecause it's semi-relevant for getting a handle on some pressure concerns.
anyone who's tried to save a hit in a balloon will notice that its quite strenuous, and you have to hold the balloon tight, avoiding poking objects while you hand it to your pal, who has presumably made room in his lungs by breathing out; and then he lets it fly. very hard to let it out gently.
and with more than 2 people, its impossibly frustrating.
get a plastic 5 gal. bucket with a lid that fits and no holes in the bucket. now procure a length of plastic pipe, about 12 inches long, and 3/4 inch diameter. swim used a swim snorkle tube beecause it was here.
now, procure a new and good plastic bag; without holes. air it out; fluff it up; make sure it is air tight by gently holding it shut and squeeze a little.
next, flatten out the bag, chasing the air out, and bunch it up at the top until you can tape it onto the end of the plastic tube. tape it good; don't worry about how it looks.
blow into the tube and try to fill the bag to make sure it doesn't leak air.
next, set the bag in the bucket, inflated to roughly the size of the bucket; get it set comfortably in there.
next, cut or melt a hole in the center of the bucket lid that will accomodate the plastic breathing tube. slip the lid over the tube, and down tightly on the bucket, squeezing out any extra air.
next, duct-tape the snorkle tube to the lid on top; it won't bee attractive, but its to keep the tube from sliding down in, or moving around much. it should bee poking out fairly straight and verticle.
next, duct tape the lid onto the bucket.
next, make another small hole in the bucket lid; dont poke the bag; should do it beefore this actually.g
and last, find a very small glass jar that will sit happily, upside down, on the open end of the breathing tube.
swim's unit could hold about 5 full exhales. test yours by setting the bucket on an appropriate chair height to make it comfortable. suck all the air out of the bag; hold tube shut w/ thumb or by setting the little jar on it; catch your breath; and inhale to your max (just air this time) and exhale into the tube, holding the hole, repeat.
when the bladder is full in there, you'll know it. you won't bee able to blow a drop more. put the inverted jar on top to keep your exhalations from escaping. the jar is plenty for this purpose, beecause, actually, the air in the bucket liner is under no strain and not needing to escape. you should bee able to come back a week later, and the bag is still full.
so, its handy to know how many hits you can stash in there beefore its full, to avoiding wasting any.
to take a hit off the bag, simply suck in. its very easy; same as normal breathing, beecause the other hole you made in the bucket lid allows outside air into the bucket, surrounding the bag as it shrinks.when you exhale in the bag, the air in the bucket comes out your second hole, with a pleasing whoosh sound. you can blow in that hole to give someone a power toke, so it might bee fun to put a tube on that exhaust portal to.
no smell; works with pot too.
after awhile, rinse some water down the tube and slosh it arond; pour it back out and consume; flavor not great, wtf.
well that was long; but it takes about 10 minutes to rig something like this; works well. looks like shit; toss a towel over it to make it pretty.no fancy parts; swim didn't need to leave the kitxchen to make it.