As someone who did prototypes/injection molds for a large company; I am baffled why a Youtuber would be doing manufacturing from the ground up like this. I was under the impression he was outsourcing all this to an overseas manufacturer.
Even Snap-On gets smaller companies to manufacturer tools for them and they just put their logo on it. There are plenty of companies that just make screwdrivers. They have been making screwdrivers for years and know the pitfalls. They know screwdrivers really damn well...
It appears that he's just wrangled an injection molding company into picking up the assembly side of things right as parts come off the machine.