[xcvbxzas]

That does not seem like much of a burden, at all.

All of that information is required knowledge for the business to operate and production to continue. You can't make something if you don't even know what materials you need to make it, nor if you don't know how to put it together.

In the case of extremely low production with hand-fitting the documented process may vary some from the actual process but it shouldn't be so significant that one product does not even resemble another.