This is now outdated. For the new improved instructable with no soldering needed, go here: http://www.instructables.com/id/Improved-Flashlight-Electronic-Cigarette-no-solder/
If you're giving up smoking, you've probably already tried (or at least heard of) electronic cigarettes - a reasonably effective way of getting hot nicotine into your system, without any of the tar or nasty cancer-causing carcinogens which come along for the ride with conventional cigarettes.
Unfortunately, the cheap ones available from petrol stations and mall kiosks don't last long and produce a negligible volume of vapour.
The more expensive models can produce decent vapour and have a more reasonable battery life, but they are not cheap, and even spare parts come at an inflated price.
This instructable will show you how to build a very powerful vapour machine with long battery life from a flashlight.
The build time should not be longer than a few hours, but significantly less if your fingers are nimbler and your soldering skills are superior to mine.