The above picture shows, how a vaporizer works, though the design is by no means what it usually looks like, due to the fact that no two vaporizers look the same.
What makes a vaporizer so unique, is that the cannabis is not actually burned, but instead the THC, along with most of the other oils/cannabinoids in the plant, is vaporised. THC's boilng point is about 395*F, so this is the minimum temperature necessary for a vaporiser to work for use with cannabis, but that is still a lot cooler than the smoke created by combustion. Not burning the plant material has several advantages:
You'll need some sort of container for the main body. In this example, a 3l baloon glas with a large cork-lid will be used, but anything will do, really. Avoid plastic however because it might melt (stating the obvious here, really, aren't I?;-) ). Drill two holes into the cork, one for the chillum and one for the tube to inhale in the end (we'll come to both of those later). If you make a hole too large, do NOT attempt to glue bits of cork back on... the glues will probably either start burning or at least give of some nasty fumes. The same applies to rubber. the best option is probably to get some more cork and stick it in together with the tubes and hope it'll stay in place. You can also try and use some wire to keep it where it is meant to be.
The chillum and the connection for the tube are best made out of copper, but obviously steel will do the job as well (though it is more expensive, and has no particular advantage). You can buy these pipes in your local hard ware shop, where it'll probably be in the plumming section. If you can't find it, don't be afraid to ask; they are everyday items so they won't ask stupid questions.
The evaporisation chamber is where you will have to put your weed in the end; it should be at least 100mm long, but not more than 150mm. The measurements given in the picture above are guidelines, so don't despair if your local hardware shop only sells pipes measured in inches or something like that (N.B.: 1 inch = 25.7mm).
The tube (which will be used to inhale the evaporised THC in the end should be about 2m (6'10") long to allow you to sit back and relax a bit, rather than having to be glued to the vaporizer at all times. It is made of PVC, 13mm thick, has a wall width of 2mm and should be available from anywhere where they sell fishtanks. If you don't like the plastic like taste of it, though, ask for one that is suitable for foodstuffs. The middle picture shows what your vaporizer should look like by now, and on the one on the right shows the most important part of your vaporizer, the thing which makes it tick, namely the hot air fan. The one used in this example is a Steinel HL 1400S with a converter piece to 20mm. If they don't have this particular one near where you live, ask for another model. Just in case you are being asked what you need it for, here are a two reasons why: pre-heating a barbecue (probably the best option)and decoloring furniture. Make sure the temperature is either adjustable or does not exceed 220*C or 410*C, and is above 395*F (whatever the corresponding temperature in *C is), otherwise it might get too hot and you'll burn your stuff after all, defeating the purpose of a vaporizer, or will be too cold making it useless. Make sure you can get a suitable converter piece for your hot air fan, so it will fit onto your vaporizer
Your final vaporizer should now look someting like this. To use, simply either put some very loosly packed weed into the evaporisation chamber, or, if you want to use hash, crumble it into really small pieces (as in tiny), and either put it in directly, or spread it over some iron wool, which you then put into evaporisation chamber. This will keep it spread apart, since it otherwise tends to stick and evetually block the pipe. I recommend that you preheat the iron wool once, to make sure that any anti-rust coating it might have is gone. And again stating the obvious: Make sure you dont' touch the evaporisation chamber during or direclty after use (unless you are wearing asbestos gloves), because it will be very hot; after use leave it for at least an hour or two. You can clean it just like you would a bong, though you'll probably really only need to clean the evaporisation chamber.
