Yes I have built a Tesla coil. It used a neon sign transformer(10kv) to fire the primary side of the coil through a couple of homemade capacitors made out of 1 foot square glass plates and aluminum foil. The primary was about 20 turns as I remember. The secondary was a couple thousand turns around a wooden dowel. The secondary sat in the middle of the primary "donut" and was air gap. I think this thing produced a couple of million volts in the micro amp range. This was wired as an auto transformer. I built it when I was twelve. I remember my Mom taking me to the sign shop to buy the neon sign tranformer. I paid fifteen dollars for it. The rest I built from scratch. I could light fluorescent lamps from 5 feet away. If you drew a line with a pencil on a piece of paper and then held the end of the trace to the top of the coil while holding the other end of the trace you could see the graphite sparkle. You didn't want to run this for too long at a time though as it produced a lot of ozone.