Yeah I’ve been here, in the US so getting raw stock in metric is prohibitively expensive. So sheet metal is where it all falls down and makes me a bit of a fibber. We would convert it to mm for the final drawings.

Before CNC’s were common I can tell you some horror stories going to a local machine shop needing it all in metric and you could hear the modem noises in their heads. We would bring them metric micrometers and scientific rulers to help them along. Mind you this was in the late 90’s and they were masters of their art, but metric wasn’t the norm in their world.