I saw another climbing arc project here and thought: Hey, why not make a tiny one!
Step 1: The transformer
First you want to find yourself a good neon sign transformer. It can be anything from 6kv to 20kv. Anything under 6kv and the spark will not spark, anything over, and you could damage the small electrodes. For this project, I used a 9kv @ 30mA made my Allenson. It will run about $10 to $20 on eBay. Or, get one from a dumpster behind a bar.
Step 2: The base
I used an old plactic container with holes drilled in it, and the electrodes hot glued into the holes. As you can see, asthetics were not crucial.
Step 3: The electrodes
You can use pretty much anything here. No more than 16 inches though, remember, we are trying to keep it small. I used a metal coat hanger cun in half. The point at which the electrodes join the base can be any small distance, BUT the electrodes will need to be bentcloser, or else the spark will not start. The basic rule of thumb is about 20kv equals 1 cm of initial gap. As the electrodes go higher, they can be flared out, up to sometimes more than 3 inches.
Step 4: Wiring
If you are unsure of how to wire up a transformer, I'm not really sure this project is for you. But, for those determined enough, I will teach you.
1) Connect the wires to the electrodes (I went up underneath, but you can got to the top of the base) 2) Connect 1 electrode to one output, and the outher electrode to the other output. 3) Connect the 120v mains, making sure that the case is grounded properly.