I just created a 100KV voltage multiplier. I bought from Conrad a mosquito zapper UV Mo-el Cricri 369 and extracted the 5KV transformer (removing diodes and capacitors), I also acquired from Aliexpress 20 capacitors 103M 20KV, and microwave diodes 20KV all for around 250 Euros. Then I built a classical diode capacitor with 2 opposite cascade. The resulting energy is 5 Joules which is a little too high for full safety so I shall add lower capacity high voltage but below nanofarad capacitors after the last stage to divide the energy by 10.
Small mult1
Small mult2