So the patterns once done would be taken to a foundry where they'd be used to make molds. I'm not totally up to speed on that process but I know it involves surrounding the pattern with a combination of refractory sand and binder. Where it gets tricky is complex parts that have multiple cores and so on.

And yeah, this guy was retired at the time but he'd been doing it for like 50 years. I'm very sure he knew what did and did not matter.