Selective laser sintering invention (Texas, ~1985)

Tom identifies this as the first modern AM process — two intersecting laser beams polymerizing a liquid photopolymer at the intersection point. Used through the late 1980s for prototyping.

One of the things I wanted to do back thirty years ago, when Ely Sachs and Mike Cima invented the term "3D printing" — they called it 3D printing because they started with an inkjet print head, and all they did was take an inkjet printer and spray the binder on a layer of ceramic powder. Wasn't really fancy, but they were able to make things immediately. That's not the first additive manufacturing. What was the first additive manufacturing? About 1985 down in Texas — selective laser sintering, where you take two laser beams in a polymer liquid, and where they intersect you get a high energy density because of the beams intersecting, and that would cause the liquid polymer to polymerize into a solid. You make this very friable, weak plastic. People jumped on that in the late 1980s for prototyping — to make parts so they could see what they would look like in building an automobile or something. It was slow, and it kind of looked like your water bottle there — kind of a gold clear plastic. They still use it for a lot of prototyping. But you never could make a structural material because it was a very specific type of polymer, a photopolymer that the laser reacted to.