I have a piece of heavy electrical cable laying on my sidewalk with the bare ends exposed. The original project was to put a flashing LED between the wires to look like sparks, but it looked really fake. I wanted real sparks. Then I found a way to do it. It's connected to a hidden car ignition coil and the pulser circuit from a cattle fence charger and a car battery. There is a long (about 1/2 inch spark between the wires due to a spark gap (a broken carbon resistor) between the conductors, which makes a very visible and loud snap. Next to the wire I placed a sign that reads "LIVE WIRE - PLEASE TOUCH". So far no one has touched it, but I've gotten lots of comments. This should get lots of attention on halloween. Several friends have gotten a good laugh out of it.