Step 6: Step 4: Electrodes
To make sealing washers, I cut 4 circles out of the tire inner tube, and then cut out the centres. Putting these on the outside, between the bolt head and the Perspex bottom, I bolted on the electrodes, L side facing out, so that the electrodes were as close to each other as possible. The bolt holes in the Perspex were 40mm away from each edge. There should only be washers between the bolt head and Perspex, not between nut and electrode, as this is where the electrical connection is made.