Items you’ll need: Screw-off beer bottle, 6inch carriage bolt with 2 nuts, heavy duty aluminum foil, a water bottle cap, salt,
cooking oil, and electrical tape.
First thing, tightly wrap the largest part of the bottle with the foil.
use a smaller piece to also cover the bottom.
cover the sides of the bottle with electrical tape so that only the bottom is exposed.
drill a hole through the cap, and mount the bolt to the cap.
next prepare a pitcher of warm water and fill it with the salt until it won’t disolve any more. distribue your brine into all of
the bottles so they all have the same salt content (in other words, don’t mix a different salt batch for each bottle or they could all
end up with differing capacitances). Also, only fill the bottle up with the salt water up to the foil level. Fill the rest of the bottle
up with vegitable/mineral oil to about an inch from the top to allow for the displacement of the bolt once submerged. The oil will
help suppress corona leakage during charging.
put a little glue or silicon into the threads of your cap, screw it on, and BAM! You’ve got cheap yet functional HV capacitors!