If you follow the instructions you should be able to get a good shock out of this that not to lethal but I'm sure its not that hard to step this up from a good shock to a powerful weapon so be responsible with this and use common sense when choosing who to shock (don't go around shocking old people, small children or any one with a heart condition its just a bad idea).
Now that thats out of the way the taser we will be building sends out about one shock per second probable around 35,000-40,000+ volts at an estimated .01 milliamp (millionth of an amp) the shock is about enough to cause you to jump back a few feet if your not expecting it. Voltage and amperage are estimated since i don't have the equipment to accurately measure it.
P.S. sorry about the low quality pictures and bad lighting my good camera was KIA I'm working on getting a replacement camera to take better pictures
UPDATE: i got a new camera enjoy the high res pictures
Step 1: Parts list
ignition coil 12v - you can get this from an old car at the junk yard for about $5. for this project you want to get one with only 2 leads. these come in all shapes and sizes so you may have to ask the people working there to help you. also try to save the mount you'll need it later but its ok if you cant
12v relay12v relay - radio shack should sell this
1000 u Farad capacitor1000 u Farad capacitor
1 u Farad capacitor1 u Farad capacitor
non conductive switch- i made the mistake of buying a metal switch and get shocked every now and then
wires- with descent insulation
12v power source - i used 8 D-cells for this
2 foot long, 1 inch thick, 2 inches wide board
6 inch long dowel 1 inch wide