What is the best material to use for the capacitor plates?
In a state of intimidation when attempting to make my first TEA laser, I had a sheet metal shop cut some pieces of .062 aluminum to use as the base and capacitor plates. I did get these pieces to work but I soon tried using ordinary aluminum foil, as I had seen others use, and found that it worked as well or better than the thicker pieces of aluminum sheet metal. The thin flexible aluminum foil has a surprising tendency to cling to the dielectric because of the electrical HV electrostatic attraction. This tends to make the capacitor have very low inductance which is necessary for a TEA laser to work.