Yeah, been watching videos of these things being done for the last hour. It is really quite simple.
microwave transformer + time = art.
Basically you just stick wires from the transformer to the wood with some kind of medium to help the electricity to flow and sit back and enjoy.
VERY dangerous but not hard.
The key are the details to get a nice pattern, a lot of the DIY are not as “pretty” as the professional ones. Thats just to to technique though.