[ZenGum]

A more controlled technique with acetylene is to use an old plastic container - PET drink bottles are good. Pass two wires through the cap, and seal with blue-tac or putty or whatever. Connect the wires to some steel wool (inside the bottle). Fill bottle with gas, screw cap on ... stand WELL back, 12 volts should do the trick.
With long tapered bottles you can get a shape-charge effect. Mount the bottle upside down with a tennis ball on top (the non-cap end)... bye bye ball!
Ahh, for all my education, I do have an atavistic streak. Things that go BANG are FUN!