This is my RQ static gap. I used 1.25 inch OD by 2.00-inch long (precut) copper pipe couplings, spaced 0.03 inches apart, and arranged in two 6-gap segments, in series. There are two 0.25 inch air intake holes located at each gap, and a 4.5-inch fan draws air through these holes directly towards the spark channels. Fearing that the hot pipes might melt the PVC enclosure, I put epoxy-fiberglass G10 spacers between the cylinders and the PVC, but this was probably unnecessary. Note the clear cover on the top, normally held in place with tape. I had initially used my vacuum cleaner motor for increased airflow, but found the additional airflow made no perceptible difference in performance. Another problem I had was mounting the fan too close to the gap elements, resulting in surface tracking arcs on the PVC cylinder. Give yourself plenty of space, and remember to ground the fan frame to your RF ground. I didn’t and I burnt out the first fan.