Jacobs ladders are great fun, and extremely easy to make. All you need is a high voltage supply and two wires mounted in a V shape as can be seen in the photos below.
The above photos of my Jacobs ladder running are running at around 16kW. And draws a whopping 75A RMS from our 240V supply. If you look carefully at the photos you can see the heat wave just before the spark. This amount of power generated a tremendous amount of heat, which can be felt at quite a distance.
In the background you can see the primary, table and Toroid from my 10" Coil.