The following is a simple design for a "vaporizer," an electric smoking device which heats your favorite hemp products to a temperature at which THC molecules wiggle enough to go airborne, but below that at which vegetable matter and tars and other nasties burn into lung-damaging smoke. Vaporizing is also more efficient since the high temperatures involved in smoking reportedly destroy some percentage of the THC. The Vapourizer page says it best:
Reasons for Vapourizing
Activation of THC acids in cannabis (decarboxylation); this occurs at around 103 degrees Celcius with vapourization at around 180-200 degrees. Smoking performs this process but is reported to destroy between 40 and 98% of the THC (Korte, Miras etc*).
The 'smoke' is much cooler and easier in the lungs.
The high is subtly different from that obtained with other methods.
The higher efficiency saves you money.
*from The Botany and Chemistry of Cannabis, Joyce and Curry (1970)
The design in that file, the first I've seen to use a soldering iron rather than an auto cigarette lighter element, is what motivated this design. This difference and the use of a dimmer switch for temperature control are the really the only essential elements of this design. There's plenty of room for creativity in its configuration and vapor enclosure, but this works for me:
What you're going to be building is essentially a soldering iron sticking out of a Pepsi bottle. The iron will be plugged into a box housing a rotary dimmer switch, allowing control of the current into the iron's heating element. A slim, high-temperature thermometer strapped to the iron's shaft helps the user stay inside the vaporization range, if one is available.
Gather:
An empty wide-mouthed soft drink container (e.g., a 3-liter bottle or a Pepsi "Big Slam" 1-liter bottle). If you can only find a 3-liter bottle, and you later find that this makes too large a vapor chamber, consider cutting out the mouth and attaching it to a 2- or 1-liter bottle.
A cheap soldering iron whose handle, at its widest point, is at least 1/4 inch narrower than the bottle's mouth. Try to find one whose tip can be unscrewed and removed, leaving a hollow space in the iron's shaft; otherwise, you'll have to devise a way of impaling some sort of heat-conducting bowl (layered aluminum foil?) on the tip. Note that I mean the very tip - many soldering irons allow the entire shaft to be unscrewed out of a small socket, but that won't do you any good. Radio Shack and other electronics shops carry soldering irons.
A cheap socket-mount rotary dimmer switch. Available anywhere basic hardware supplies are sold.
A case for the dimmer switch. A very good choice is a plastic 10-disc 3.5 inch floppy box.
A slim high-temperature thermometer, small enough to fit snugly against the shaft of the soldering iron (i.e., not a big round oven thermometer) and including the range 150-250 C. [Optional]