How to build a high voltage capacitor for cheap

This video shows you a step by step process on how to build a home made high voltage capacitor for little to no money at all.
In case you haven't noticed by now, the price of high voltage capacitors on the market is annoyingly high compared to their performance. For example a low quality 15 kV/1 nF capacitor can get up to 3 usd a piece.

In this video I'll show you how to build a big high quality 100 nanofarad high voltage capacitor with roughly the same amount of money and few minutes of work. In the following video I have successfully tested the capacitor to 30 kilovolts.

The capacitor worked incredibly well given the fact that it took over 12.5 times the nominal voltage rating to damage the dielectric.
However I believe one of the main reasons for breakdown were tiny hit marks on plastic foil from inadequate storage. Ultimately I believe this was the reason which caused it to puncture under high voltage.