The electrode is the part that actually receives the high-voltage signal generated by the WEFT Engine. I’ve included a few actuation boards to experiment with after the workshop is over. You should also try other materials! Aluminum cans work well because they have a foodsafe coating that functions well as a dielectric. Bare copper has been working on and off for me as well, as long as I give the copper some time to grow an oxidized coating. Anodized aluminum is supposed to work well, but it hasn’t, yet, for me.
How to hold the electrode:
JFYI,…the electrode you have received has a third pad (in addition to the center copper pad and the side ground pads). On the backside of your electrode board, you can see that there’s a pad covered by soldermask. This was an experiment I ran to see if soldermask will function as a good dielectric. So far, the results have been bad—I haven’t been able to send any signals through the pad that result in a perceivable feeling.