well, its my first instructable so it may be bad if you put bad critics i wont see them but if there are questions i'll answer.
it's very cheap, like 10 bucks or less.is a shock machine, its very funny to put to max level and see the face of the other guy.
its high voltage but low current (it's like 40 v .5 Amp)
Step 1: components
you will need:
1 Variable resistor 100 K
1 Transformer for 12 V with central derivation
1 NPN transistor TIP31C
1 Resistor 560 OHM
1 or 2 battery clip (for 4 AA batteries)
4 AA batteries
2 Copper tubes
a lot of wire