It's only hard because he's insisting on re-inventing everything rather than just using standard engineering practices. I used to build test equipment for aero

It's only hard because he's insisting on re-inventing everything rather than just using standard engineering practices. I used to build test equipment for aerospace and safety critical equipment for coal mining. I'm well aware that even with rigorous control you're going to get some errors. But "the glass fell out because we glued it wrong" isn't a normal manufacturing error. It's a mistake that requires more than one process to fail.