Prior Context
Before the 1980s, manufacturing complex three-dimensional objects almost always relied on subtractive methods, such as cutting, drilling, or machining material away from a solid block, or on molding processes that required expensive, custom-made tooling for each design. A distant conceptual precursor existed in the nineteenth century: in the 1860s, the French sculptor François Willème developed a technique called photosculpture, which used multiple cameras arranged around a subject to capture contours that a craftsman then carved by hand, an early attempt to translate a captured three-dimensional form into a physical object, though it required no digital data and no automated building process.
These traditional manufacturing approaches made rapid experimentation with new shapes slow and costly, since any design change required reworking or replacing physical tools and molds. Engineers and designers increasingly sought a faster way to turn digital design files into physical prototypes without the delays of conventional manufacturing. At the same time, advances in computer-aided design software during the 1970s and early 1980s, including early commercial systems such as CATIA, introduced by the French company Dassault in 1977, gave designers the ability to create precise three-dimensional digital models, but no widely available technology yet existed that could translate those digital models directly into solid physical objects, a gap that set the stage for the earliest additive manufacturing experiments.
Historical Development
The earliest documented concept resembling modern 3D printing came from Hideo Kodama, a researcher at the Nagoya Municipal Industrial Research Institute in Japan, who in 1980 and 1981 described, and published in the journal Review of Scientific Instruments, a system for building a solid object layer by layer using a photosensitive polymer that hardened when exposed to ultraviolet light, directed either by a mask or a laser beam traced over each cross-section. Kodama filed a patent application in Japan for this rapid-prototyping concept, but it lapsed before completion, reportedly due to insufficient funding to pursue the filing within the required period, and he did not commercialize the technology.
A few years later, in 1984, the American engineer Chuck Hull, then working at a company called UVP, Inc. in California that made ultraviolet coatings, independently developed a similar process, which he named stereolithography, using an ultraviolet laser to selectively cure successive thin layers of liquid photopolymer resin into a solid three-dimensional shape. Hull filed a patent application for stereolithography in 1984, and the patent was granted in 1986; that same year he co-founded 3D Systems Corporation in Valencia, California, to commercialize the technology, and the company released the first commercial stereolithography machine, the SLA-1, in 1987. Other additive manufacturing processes followed quickly: Carl Deckard, a graduate student at the University of Texas at Austin, developed selective laser sintering, which fuses powdered material with a laser, filing a patent in 1986 that was granted in 1989. Separately, engineer Scott Crump developed fused deposition modeling after experimenting with a hot-glue gun to build a small object layer by layer; he patented the extrusion-based process in 1989 and, together with his wife Lisa Crump, co-founded Stratasys in Minnesota to commercialize it. Together, these distinct processes, developed independently within a few years of one another, established the foundation of what became known collectively as 3D printing.
Key Participants and Institutions
Hideo Kodama's early 1980s photopolymer layering experiments, conducted at a Japanese industrial research institute and published in a scientific instruments journal, represent the first documented technical description of what would later be called additive manufacturing, even though his patent application was not completed and the concept was not commercialized at the time. Chuck Hull is credited as the inventor of stereolithography and the primary commercializer of 3D printing, since his 1984 patent, developed while he worked at a small California coatings company, and his subsequent founding of 3D Systems turned the underlying concept into a functioning industry.
Carl Deckard, working within a university research setting, and Scott Crump, working independently as an engineer, each developed alternative additive processes, selective laser sintering and fused deposition modeling respectively, broadening the technology beyond photopolymer resins to powders and thermoplastics. Crump's co-founding of Stratasys with his wife Lisa Crump, and Deckard's university-linked patent, expanded the field's commercial reach through the late 1980s and into the following decades.
How It Works
All 3D printing technologies share a common underlying principle: a three-dimensional digital model is mathematically sliced into a series of thin, two-dimensional cross-sections, and a printer then builds the physical object by depositing or solidifying material one cross-sectional layer at a time, with each layer bonding to the one beneath it until the complete object emerges from a build platform.
The specific method of forming each layer varies by process. Stereolithography lowers a platform into a vat of liquid photopolymer resin and uses an ultraviolet laser, guided by mirrors, to trace and harden only the resin within each layer's cross-section before the platform shifts down slightly for the next layer. Selective laser sintering spreads a thin layer of powdered material, such as nylon or metal, across a build area and uses a laser to fuse the powder particles together only where the cross-section requires solid material, leaving unfused powder in place to support the part as more layers are added. Fused deposition modeling melts a thermoplastic filament and extrudes it through a heated nozzle that moves in a pattern tracing each layer's outline, depositing material much like a computer-controlled glue gun. Because the object is built up gradually rather than cut from a larger block, additive manufacturing can produce complex internal shapes and geometries that would be difficult or impossible to achieve with traditional subtractive methods.
Dates and Milestones
- 1980-1981Hideo Kodama describes an early layer-by-layer photopolymer rapid-prototyping system in Japan.
- 1984Chuck Hull independently develops stereolithography and files a patent application.
- 1986Hull's stereolithography patent is granted; 3D Systems Corporation is founded.
- 19873D Systems releases the SLA-1, the first commercial stereolithography machine.
- 1989Patents for selective laser sintering and fused deposition modeling are granted; Stratasys is founded.
Impacts
Additive manufacturing transformed product development by allowing designers and engineers to produce physical prototypes directly from digital files within hours rather than the weeks required by traditional tooling, dramatically accelerating the design and testing cycle across industries from automotive and consumer products to footwear and toy design. The technology also enabled forms of manufacturing not practical with subtractive methods, including customized medical implants and prosthetics shaped to an individual patient's anatomy using medical scan data, lightweight aerospace components with complex internal structures that reduce weight on aircraft and spacecraft, and intricate architectural and artistic models used throughout the design process.
As patents on the earliest processes, including Crump's fused deposition modeling patent, began expiring in the late 2000s and early 2010s, lower-cost desktop 3D printers, based largely on fused deposition modeling, became available to hobbyists, schools, and small businesses, expanding the technology from specialized industrial use into classrooms, maker spaces, and home workshops around the world. This broader availability also spurred an active open-source hardware community that further drove down the cost of personal 3D printers through the 2010s.
Limitations
Despite decades of progress, 3D printing has not replaced conventional manufacturing for most mass production, because it remains considerably slower and, per unit, more expensive than injection molding or machining when producing large quantities of identical objects. The range of materials usable in additive processes, while expanding, is still narrower than the full range available to traditional manufacturing, and printed parts can show layer lines or structural weaknesses along the boundaries between layers that require additional finishing, orientation planning, or engineering workarounds.
The overlapping patents filed by Kodama, Hull, Deckard, and Crump also generated years of legal disputes over the scope of ownership of various additive manufacturing techniques, which shaped how and when competing companies could enter the market and offer machines using similar processes.
Common Misconceptions
3D printing is often described as if Chuck Hull invented the entire concept from nothing in 1984, but Hideo Kodama had already described a comparable layer-by-layer photopolymer process several years earlier, even though his patent lapsed and his work was not commercialized; Hull's distinct achievement was completing a patent, naming the stereolithography process, and building the company that brought it to market.
It is also a misconception to treat '3D printing' as a single technology; the term actually covers several fundamentally different processes, including stereolithography, selective laser sintering, and fused deposition modeling, which use different materials and physical mechanisms to achieve the same general goal of building objects layer by layer.
