I'm working on getting the parts together for this project. Part of me wishes that the kit was still available somewhere, but thankfully there are still a few resources out there.
3D print files
I contacted a local 3D printer, and they were able to find the above link to all the pieces, minus the vacuum tubes, needed for the Tesla Gun. I don't intend to use all of them, mostly for the silver handle part, and the brass barrel, and the things to connect the vacuum tubes and button.
I'll be using a Raspberry Pi Pico, a Neopixel Mini Button PCB, and one of the buttons that came with my PIco starter kit as the trigger. I may also try to add in something that would set the dials going when it's fired but I'm not sure yet how to do that. I will also use a potentiometer from my starter kit to dial up and down the 'power' or how bright the light will be.
I am hoping I'm able to find these or something very similar to use.