Recommended · for some experience
400kV High Voltage Generator (Stun Gun Module?) - with schematic
Why people recommend it
Cited for its teardown and reverse-drawn schematic of a cheap high voltage module, revealing an oscillator, transformer and voltage multiplier inside.
Watch for: High voltage hazard; narration can be hard to follow
In their words
Such a configuration is seen in this tear-down video.
Horror Vacui on electronics.stackexchange.com, May 2020. CC BY-SA.