He built the wing in small sections. He made two templates of wing cross section and attached them to the foam. Then he drilled holes through the them , and the rest were done with a hotwire.
According to what he said. He built the planes and flew them once or twice and hang them up and probably never touch them again.Any idea how much time he has on any of his airplanes?
I think all he does is to build thing to make youtube videos for a living and airplanes just happen to be one of those things he builds. Socialblade shows his cut from the videos could be as much as 20K+ per month and he's got more than 1.4 million subscribers. He's also getting $500+ per month on patreon subscriptions.