For the record, I (an engineer) test my own designs (both installation and performance) and sometimes fab them myself to identify pain points, something I encourage for all engineers.

Not as clever as a machinist when it comes to techniques for manufacturing, but I generally try to avoid the need for such techniques if I can. But sometimes it’s necessary.

This is also how engineers look at other engineers (damn engineers, they ruined engineering!)

It’s not the engineers fault that another engineer hasn’t yet invented a machine that can make what he designed.