Do you like fog machines? Do you like fog machines that can go in your pocket?
That is what an e-cigarette is. A fog machine that produces fog when you suck on it. The "e-liquid" is actually the same, or a very similar chemical to the one found in fog machines. And they work the same way (save for the sucking). Current is delivered to a resistance heating wire that is in contact with the chemical. The chemical then vapourizes and makes the fog.
I have converted the e-cig cartridge so that it draws power from a wall wart power adaptor, and is activated by a button. With a good battery, you could have one of these in your coat pocket!
Here is some info on it:
Basic pushbutton switch circuit.
Greensmoke E-cig cartridge refilled with vegetable glycerin. Inside it, a wire gets red hot, and vapourizes the glycerin.
Solder wires on instead of battery.
Don't hack adaptors that you use for other things. You are very likely to break burn them out or otherwise destroy them. Read the output in volts and in mA. A smoke machine uses heat, which means high amperage. These adaptors are less common.
Adaptor output MUST deliver at least 2 Amps and at most 4.5 volts. If not, this is like short circuiting it and could destroy it.
Do not use a switch that stays on - you could cause a fire.
Here is the video:
Here is a picture: