I've tried it before and it works pretty good with changa. Your going to want to have a separate whip/bowl piece for changa than for herb, i find a short whip with a 14mm gong male attachment on the other side put into a jhook, small bubbler, or small bong works best.
As far as temps, anywhere from 60-90C should do the job. DMT FB vaporizes at 60-80C, and a little bit over probably wont burn it. I'd just start at 60C and bump it up 5C at a time until you get nice vapor, then a few degrees more to ensure its hot enough.
Just be careful using crystal spice in it, even sandwiched between plant material, as it can melt and drip down on the heating element due to the upside down bowl design.
Don't use bags either, far more surface area/time the vapor is in contact with it, and your going to lose more to condensation than a narrow short vapor path. Like using a 6-12" whip with a 14mm gong attachment to a 14mm jhook, or small 14mm bubbler.
Bongs seem a bit overkill imho, and you'll prob lose the most to condensation with them after bags of course. Plus its easier to clean a small bubbler or jhook than a bong if you don't want to dedicate a piece of glass for dmt vaporizing.
Let us know how it works if you do try it, I've only done it a few times, but it worked pretty well with changa.
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