Back in the old days when movie theaters used carbon torch lights in their projectors carbon sticks were common, then there were carbon torches that attached to electric welders, at about the same time with the same equipment there were spot ‘annealers’..
http://en.wikipedia.org/wiki/Carbon_arc_welding
Carbon sticks come in a range of diameters, the one I used and still have used a spark plug metal body for an insulator, all that is required is a 12 volt battery, two leads, one attached to the receiver, the other to the carbon stick, the carbon stick should have a point at contact.
It is advised to practice, arching un-nerves most, 12 volts can cause the user to hurt themselves, there is little danger of being shocked.
F. Guffey
The carbon torch uses two carbon sticks.