Jim Wilkins wrote:

The genesis of 3D printing was the piezoelectric ink jet that
accurately shot out tiny well-controlled single spherical drops of
125C molten plastic. It took a lot of time and effort to learn how to
do that, instead of multiple or wildly wobbling drops of varying size.
The basic idea is as simple and obvious (and crude) as piling up drops
of wax or hot-melt glue.
-jsw

Sometime in the 2nd half of the 80s, on one of my visits to MIT, I was
taken across campus by my host and shown a project he was consulting
on: A 3D printer jury rigged from a dot matrix printer, a computer or
two and a mare's nest of tubes and cables.

They were experimenting with several media but when I was there, they
were using tiny metal spherules, laying down strata consisting of a
pattern of glue followed by a uniform layer of metal powder, one line
at a time. The result, after excess, unglued powder removal, was
sintered and then permeated by osmosis with a different low-melting
point metal. Biggest object would about fit in a 4" or 5" cube.

I have no idea whether those guys are all millionaires now or if they
shingled off onto the fog and the big bucks landed elsewhere.

--
Mike Spencer Nova Scotia, Canada