I will say this. It is dangerous as hell, but I have dealt with this for a while. You are wiring up the innards from an old microwave. You can also use the converters/inverters from neon signs.
Neon signs do smaller burns and need more contacts.
Microwaves do deeper burns and give that nice lightning mark.
Microwaves are more dangerous because of their power. High voltage, but higher amps. This is why they are dangerous.
Never do this. I am close to an electrical engineer, I have worked with elecriticy for 20 years.I made mine safe and I was still scared of it.