Still, I think some of my point can still be salvaged - this implies that it was patented in the early 80s, which by my reckoning is still well after it became possible.
Possible, yes. Economically viable for the vast majority of applications, no.
In undergrad in 2001 I had a professor that had a 3D printed airplane model with a wingspan of ~5" that he thought was so damn cool (it was some now-defunct military airplane he helped design or something). He was also very fond of pointing out that the model cost his former employer $500 to print, so we better handle it with care. And rightfully so, because if we treated it like a toy it would have fallen apart in under a semester. Compared to what I print today using my MK3s for, I dunno, 50 cents, his $500 printed airplane was a piece of crap.
Point is there have been a lot of technological advances, patents aside, that have made 3D printers viable for anything outside of extremely high-value rapid prototyping / mold forming / other narrow niche applications in the last 20 years.
Still, I think some of my point can still be salvaged - this implies that it was patented in the early 80s, which by my reckoning is still well after it became possible.