A vaporizer is a electronic device in which the "essential oils" (from cannabis) are converted into a gas to be inhaled. The machine heats an element and marijuana is then placed next to the heating source to be converted to a vapor. I suggest buying a vaporizer where the temperature can be set manually by the user.
A vaporizer can save upwards to 70% of the THC from being destroyed by the intense heat from a flame, and will vaporize around 95% of the Trichomes. Making for a much larger dosage and high that will not necessarily last longer than normal but is stronger and more clear-minded. Non of that feeling foggy and retarded. Also, the amount of inhaled carcinogens is greatly decreased over smoking. If used correctly the carcinogens should be reduced to practically zero due to fact little or none of the matter ignites.
There are two types of vaporizers on the market that I will endorse, they work either like the brands Volcano or Digi-Vapor. Brands like the Volcano use a fan to push the air over the heating source while brands like the Digi-vapor do not, relying on the person's lungs to pull the vapors. One type isn't better than the other, but one will fit the users needs better. The Volcano type has a tray that slides in over the blowing hot air and the vapors collect in a bag. These types are good for people with weakened lungs, and are short of breath. Now, the Digi-Vapor kind will have a glass on glass structure known as whip or a hands free kit. It's a 18mm wide female bong stem looking piece with a polyurethane tube attached at the other end. The whip slides on the heating source after being filled with the desired substance, and that's it. Just suck it.
If the heating source is set at a high temperature it works best to pull in the air a little faster, but if it's set at a lower temperature it's better to draw more slowly. This idea will also work as well when setting the fan speed too on the other types.
Vaporizers allow so much more play in the way weed is consumed over smoking. Different types of highs can be obtained just by changing the temperature at which the heat source is set. This happens because of the 419 some odd compounds in marijuana, the lighter molecules turn to gas faster. It's possible to get high several times on a single bowl by starting with the lighter molecules and turning up the temperature to get at the heavier ones. I call this re-vaping, and it increases the effectiveness of the machine at converting all the potential oils.
In my personal opinion, the vaporizer is the best thing to be invented since the joint, and is bud's new best friend. Who ever rolled and smoked weed first was a genius, but the first person to figure out it was possible to get high without the combustion was the smartest person ever. But, the people who first thought they could make a vaporizer using a light bulb or heat gun have smoked themselves retarded, and are not the best people to receive information.
For starters, light bulbs are filled with a powder that must be cleaned out first. Which is next to impossible to remove all of that fine crap. Inhale this matter and it's kinda is defeating the purpose of vaporizing for a healthy life style. Not to mention the inability to keep the heat at a constant makes things harder than they need to be, and the list goes on why you should not use a light bulb. The third type of vaporizer is a heat gun isn't any better than the light bulb. There are no substitutions for this type either, no matter the price range, real heat guns will run too hot to vaporize marijuana. But back to the devices used for weed, they're desgined to work with a bong, and the vapors are filtered through water, which is bad because the vapor molicule is much smaller than that of smoke, so the water doesn't do anything but trap the stuff that gets you high.
The temperature range to vape weed is around 110C/230F to 200C/390F(Boiling point of THC). Heat guns are made to do other things and the factory settings will be too high, the weed instantaneously ignites causing smoke rendering any attempt at vaporization futile. Also, when it ignites by spontaneous combustion it tastes like straight asshole. So, I don't know why people keep doing it. Stop it! Just buy the real thing already. They cost about the same price as a heat gun. Anyway, there isn't a home-made vaporizer that can stand up to hot-knifing.
Purchasing a vaporizer and using it correctly will save greens, plus the whole getting annihilated without the unhealthy smoking part.