This is my single static vacuum gap. I made it from standard 1" copper pipe fittings joined together by a PVC pipe "Tee" connector. The base of the gap is a 120V/10 Amp vacuum cleaner motor salvaged from a very powerful Hoover canister-type vacuum cleaner. The motor sucks a huge volume of air through the hollow electrodes to blow out the arc and to carry away heat. I got the idea for this gap from expert coilerGary Lau, who showcased a similar gap on his web page. However, I elected to use a lot more copper in my gap to sink more heat, as I anticipate running at progressively higher power levels. This massive gap gives me room to grow, perhaps up to a few KVA before I must forsake it for a rotary gap. Running at over 3KVA from my twin MOT supply, the gap faces barely warm above room temperature, even on 1 minute runs. The speed is variable over a wide range via a simple dimmer switch power control. However, full blast seems to work best. Whether I'm using the NST or the MOT supply, the gap roars like a chain saw, and hearing protection is mandatory. This is a crude, brute-force approach to spark gap design, but it sure gets the job done.