It is an interesting question, but kind of outside the scope of this forum. You should conduct a study on Additive Manufacturing History. There are many textbooks on the subject. In general, I believe the first patent described it as Rapid Prototyping using plastics(late ~1970s). Metal Additive was not introduced until early ~1990s. I believe it was originally researched at Wake Forest and MIT, but there were probably other institutions and corporations researching this in parallel as well.
You are navigating away from the AIS Discovery experience