[rocketman221] wrote up one of the simplest ways to build a high voltage power supply. This one in particular was used on his coilgun. Instead of building a custom circuit, he’s using flash charging boards from disposable cameras. Six 450V 470uF caps are wired in parallel to make up the bank. Two of the charger boards are wired to one switch to initiate the charging process. Four additional boards are wired two a second switch for the second charging stage. The part cost on this is incredibly cheap and it only requires a 3.3V input to reach 450V. The writeup has plenty of warnings about the dangers of high voltage; you need to clean off all flux residue to prevent arcing across the circuit boards. Embedded below is a video of the bank being discharged through several objects.