Hammeron wrote
Not for me for my younger brother, 13.
He is very very good with his hands and focuses well.
Several self-taught repair guys (and even a builder) I have spoken to remarked that they initially started trying to do their own repairs because nobody else was available. Then word got out and all sorts of people started bringing them guitars.
This is where you brother needs to play his cards very carefully. People WILL bring him guitars, and they may have unreasonable expectations around his levels of skill (I know that he's good with his hands, but he'll be on a learning curve), the time that the job will take etc. Plus violins, mandolins and all sorts of other stuff will soon beat a path to his door.
This could get especially difficult if he doesn't have a more experienced person to advise him and who he can refer work to if he feels out of his depth.