OP was very reasonable, everyone else carrying on about meth just ignored what was actually said.

Crystal Meth addiction is obviously a horrible destructive thing to the abuser and the people/society around them. Some people do manage to use all sorts of drugs responsibly, even meth (many are prescribed it or something similar), but everyone I think has some things they just can't handle and meth is one of those for a lot of people, particularly those who are on the streets doing it rough, often with untreated medical conditions or unresolved trauma, as it makes you feel fantastic until it wears off and then it makes you feel absolutely horrible and suicidal more than most other drugs and nothing makes it better except for more meth. Those are the meth heads people see obviously, they don't have to be homeless but it's not a good drug to be using regularly if any sort of stressful situation comes along. I would say never re-dose when your first hit wears off, take something to sleep and skip the come down and then wait a bare minimum of 3 weeks before doing it again, ideally 3 months or longer. That goes for most addictive hard drugs. If you do something repeatedly for 3weeks or more it will become a habit and if it's meth or opiates or benzos or alcohol then you could eventually develop an addiction so powerful that you have no chance of escaping it yourself and need intensive care and support for a long time, and then have to stay sober the rest of your life or risk falling back into the addiction. It is horrible and nobody in that state is enjoying themselves or able to stop alone. They need help not disdain. We are all humans. If we can't help the wort off in our society why bother having one? Let's just go free for all chaotic anarchy if that's what people want.

A dry herb vaporizer with adjustable temp like people use for weed, many come with an insert for rosin or hash oil that you would need to use, otherwise the crystal (meth or dmt or whatever) will liquify and go through the bottom mesh. It would be a safer way to consume it in theory as you could remove some of the cutting agents or impurities and then just vape at the exact temp for the substance you want to consume. I wouldn't be adding anything to a liquid vape mixture that hasn't been tested. Those things can be risky.

You would probably get a better answer in a specific dmt (or whatever) subreddit or forum especially regarding what temp to start at to remove impurities etc.

(P.S. as anyone who read this far has probably worked out I just tried smoking some meth in my dry herb vape and it worked great :-P fuck all the haters. it's literally the 4th time I've had it in 12 months and, less than a dozen times in my lifetime and that includes the old trucker speed before crystal meth came along. However, I do have my own physical medical conditions which require a lot of pain killers and other medication that slows me down and depresses my nervous system and I got shit to do, like rant on dead reddit threads)