Also keep in mind once a neon tube is triggered it won't shut off until the voltage falls below about a third of the striking voltage.
Just wondering if another PCB on top will create enclosure with edges filled with solder, etc, than a few strikes inside this thing can increase temperature and lower air break voltage, I guess?
It was a little bit art work, but final esd gap like this could have copper traces cut on laser CNC and put inside two PCBs to (like one bottom here) spot welded using 1000A pulses, to glue everything together and catch air at given humidity inside
This way ESD from sharp edges could hit into 1mm copper plate walls inside between PCB top/bottom walls
In this prototype, probably will add on top another PCB with 4 holes and screw them together.
Now thinking, how to test this thing-probably will use transformer from microoven teardown and add a few stages of a few kV voltage doublers to make something like preconditioning-hit a few HV strikes to ensure this ESD gap copper rings soldered later will enable breakdown at lower voltage later
Probably this is not needed if 1mm CNC copper plates will be used instead of this temporary copper rods and solder art work