One of the hardest parts of telling any history, is which innovations are significant enough to warrant mention. Too much, and the history is so vast that it can't be told. Too few, and it's incomplete. Arguably, no history is ever complete. Yet there's a critical path of innovation to get where we are today, and hundreds of smaller innovations that get missed along the way, or are out of scope for this exact story.

Children have probably been placing sand into buckets to make sandcastles since the beginning of time. Bricks have survived from round 7500BC in modern-day Turkey where humans made molds to allow clay to dry and bake in the sun until it formed bricks. Bricks that could be stacked. And it wasn’t long before molds were used for more. Now we can just print a mold on a 3d printer.
 
A mold is simply a block with a hollow cavity that allows putting some material in there. People then allow it to set and pull out a shape. Humanity has known how to do this for more than 6,000 years, initially with lost wax casting with statues surviving from the Indus Valley Civilization, stretching between parts of modern day Pakistan and India. That evolved to allow casting in gold and silver and copper and then flourished in the Bronze Age when stone molds were used to cast axes around 3,000 BCE. The Egyptians used plaster to cast molds of the heads of rulers. So molds and then casting were known throughout the time of the earliest written works and so the beginning of civilization.

The next few thousand years saw humanity learn to pack more into those molds, to replace objects from nature with those we made synthetically, and ultimately molding and casting did its part on the path to industrialization. As we came out of the industrial revolution, the impact of all these technologies gave us more and more options both in terms of free time as humans to think as well as new modes of thinking. And so in 1868 John Wesley Hyatt invented injection molding, patenting the machine in 1872. And we were able to mass produce not just with metal and glass and clay but with synthetics. And more options came but that whole idea of a mold to avoid manual carving and be able to produce replicas stretched back far into the history of humanity.

So here we are on the precipice of yet another world-changing technology becoming ubiquitous. And yet not. 3d printing still feels like a hobbyists journey rather than a mature technology like we see in science fiction shows like Star Trek with their replicators or printing a gun in the Netflix show Lost In Space. In fact the initial idea of 3d printing came from a story called Things Pass By written all the way back in 1945!

I have a love-hate relationship with 3D printing. Some jobs just work out great. Others feel very much like personal computers in the hobbyist era - just hacking away until things work. It’s usually my fault when things go awry. Just as it was when I wanted to print things out on the dot matrix printer on the Apple II. Maybe I fed the paper crooked or didn’t check that there was ink first or sent the print job using the wrong driver. One of the many things that could go wrong. 

But those fast prints don’t match with the reality of leveling and cleaning nozzles and waiting for them to heat up and pulling filament out of weird places (how did it get there, exactly)! Or printing 10 add-ons for a printer to make it work the way it probably should have out of the box. 

Another area where 3d printing is similar to the early days of the personal computer revolution is that there are a few different types of technology in use today. These include color-jet printing (CJP), direct metal printing (DMP), fused deposition modeling (FDM), Laser Additive Manufacturing (LAM, multi-jet printing (MJP), stereolithography (SLA), selective laser melting (SLM), and selective laser sintering (SLS). Each could be better for a given type of print job to be done. Some forms have flourished while others are either their infancy or have been abandoned like extinct languages.

Language isolates are languages that don’t fit into other families. Many are the last in a branch of a larger language family tree. Others come out of geographically isolated groups. Technology also has isolates. Konrad Zuse built computers in pre-World War II Germany and after that aren’t considered to influence other computers. In other words, every technology seems to have a couple of false starts. Hideo Kodama filed the first patent to 3d print in 1980 - but his method of using UV lights to harden material doesn’t get commercialized. 

Another type of 3d printing includes printers that were inkjets that shot metal alloys onto surfaces. Inkjet printing was invented by Ichiro Endo at Canon in the 1950s, supposedly when he left a hot iron on a pen and ink bubbled out. Thus the “Bubble jet” printer. And Jon Vaught at HP was working on the same idea at about the same time. These were patented and used to print images from computers over the coming decades.

Johannes Gottwald patented a printer like this in 1971. Experiments continued through the 1970s when companies like Exxon were trying to improve various prototyping processes. Some of their engineers joined an inventor Robert Howard in the early 1980s to found a company called Howtek and they produced the Pixelmaster, using hot-melt inks to increment the ink jet with solid inks, which then went on to be used by Sanders Prototype, which evolved into a company called Solidscape to market the Modelmaker. And some have been used to print solar cells, living cells, tissue, and even edible birthday cakes.

That same technique is available with a number of different solutions but isn’t the most widely marketable amongst the types of 3D printers available.

SLA
There’s often a root from which most technology of the day is derived. Charles, or Chuck, Hull coined the term stereolithography, where he could lay down small layers of an object and then cure the object with UV light, much as the dentists do with fillings today. This is made possibly by photopolymers, or plastics that are easily cured by an ultraviolet light. He then invented the stereolithography apparatus, or SLA for short, a machine that printed from the bottom to the top by focusing a laser on photopolymer while in a liquid form to cure the plastic into place. He worked on it in 1983, filed the patent in 1984, and was granted the patent in 1986. 

Hull also developed a file format for 3D printing called STL. STL files describe the surface of a three-dimensional object, geometrically using Cartesian coordinates. Describing coordinates and vectors means we can make objects bigger or smaller when we’re ready to print them. 3D printers print using layers, or slices. Those can change based on the filament on the head of a modern printer, the size of the liquid being cured, and even the heat of a nozzle. So the STL file gets put into a slicer that then converts the coordinates on the outside to the polygons that are cured. These are polygons in layers, so they may appear striated rather than perfectly curved according to the size of the layers. However, more layers take more time and energy. Such is the evolution of 3D printing.

Hull then founded a company called 3D Systems in Valencia California to take his innovation to market. They sold their first printer, the SLA-1 in 1988. New technologies start out big and expensive. And that was the case with 3D Systems. They initially sold to large engineering companies but when solid-state lasers came along in 1996 they were able to provide better systems for cheaper. 

Languages also have other branches. Another branch in 3d printing came in 1987, just before the first SLA-1 was sold. 

Carl Deckard  and his academic adviser Joe Beaman at the University of Texas worked on a DARPA grant to experiment with creating physical objects with lasers. They formed a company to take their solution to market called DTM and filed a patent for what they called selective laser sintering. This compacts and hardens a material with a heat source without having to liquify it. So a laser, guided by a computer, can move around a material and harden areas to produce a 3D model. Now in addition to SLA we had a second option, with the release of the Sinterstation 2500plus. Then 3D Systems then acquired DTM for $45 million in 2001.

FDM
After Hull published his findings for SLA and created the STL format, other standards we use today emerged. FDM is short for Fused Deposition Modeling and was created by Scott Crump in 1989. He then started a company with his wife Lisa to take the product to market, taking the company public in 1994. Crump’s first patent expired in 2009. 

In addition to FDM, there are other formats and techniques. AeroMat made the first 3D printer that could produce metal in 1997. These use a laser additive manufacturing process, where lasers fuse powdered titanium alloys. Some go the opposite direction and create out of bacteria or tissue. That began in 1999, when Wake Forest Institute of Regenerative medicine grew a 3D printed urinary bladder in a lab to be used as a transplant. We now call this bioprinting and can take tissue and lasers to rebuild damaged organs or even create a new organ. Organs are still in their infancy with success trials on smaller animals like rabbits. Another aspect is printing dinner using cell fibers from cows or other animals.

There are a number of types of materials used in 3D printing. Most printers today use a continuous feed of one of these filaments, or small coiled fibers of thermoplastics that melt instead of burn when they’re heated up. The most common in use today is PLA, or polylactic acid, is a plastic initially created by Wall Carothers of DuPont, the same person that brought us nylon, neoprene, and other plast