Any guess what process created this ?

[Tailmaker]

As a teenager (maybe 13?) I played around with a salvaged ignition transformer of an oil furnace. Likely 6000 V and unknown amperage. After making great sparks and arcs I found it created such beautiful patterns. It happened to not kill me, but my dad slapped me hard since he did not appreciate the patterns in his work bench surface.

[Xxray]

Here is a little guitar I zapped, think I am going to epoxy fill the burns but I got to be careful, one at least overruns the edge so I have to make a little putty dam to stop it from flowing down the side.
Not worried about this work changing the dynamics of the tone ect, cheap little travel guitar, maybe it will sound better.