杏吧原创

Around the world, thousands of people who are missing limbs are wearing custom-fitted replacements. In operating theatres, surgeons are using 3D replicas of their patients鈥� bodies to guide operations. That鈥檚 the kind of thing that makes Chuck Hull very, very happy 鈥� because he invented the technology that made it possible. 鈥淚鈥檝e been the most surprised and impressed by the advances 3D printing has enabled in healthcare,鈥� Hull says. 鈥淚t鈥檚 an amazing feeling to contribute to saving and improving lives on such a fundamental level.鈥�

Thirty years ago that was unthinkable. Making things like prosthetic limbs 鈥� or even plastic widgets 鈥� was notoriously difficult. 鈥淓very engineer knew how tedious it was,鈥� Hull says. 鈥淵ou would design a part and make blueprints that you give to a designer. Then you need a machinist. Then, finally, you鈥檇 go to the injection moulder.鈥� And if it wasn鈥檛 right, you had to go through the whole process again. Manufacturers were desperate for a better way. 鈥淣obody had a solution for this 鈥� and that was the point of 3D printing,鈥� Hull says. 鈥淭he idea was simply to prototype plastic parts. It doesn鈥檛 sound very imaginative given how exciting 3D printing has become.鈥�

Hull is being typically modest: back in 1983 his idea was a flash of inspiration. At the time, he was working for a small US company using high-intensity UV light to set, or cure, liquid plastic into solid. One of its products was a coating for a table. 鈥淎t some point it occurred to me that we were curing really thin pieces of plastic,鈥� Hull says. 鈥淚 thought, maybe there was some way I could stack up these sheets to create prototype parts.鈥�

If he could make it work, it would slash production times from months to days. 鈥淚 went to the head of the company all excited, saying, 鈥楬ey, we鈥檝e got to work on this鈥�.鈥�

He didn鈥檛 get very far. Despite Hull鈥檚 enthusiasm, his boss was reluctant to gamble valuable resources on a future in layered plastic. But Hull kept arguing his case. 鈥淚 was confident that I could figure out how to do it,鈥� he says. Eventually, his boss agreed to let him have an empty lab at the back of the building. But he couldn鈥檛 use it in company time. He had to work on the idea at evenings and weekends.

He started with the motors found in pen plotters 鈥� machines that draw things like building plans 鈥� and programmed their motion on a primitive computer using BASIC. It was laborious work. 鈥淵ou had to envision it in your head and program in, line by line, the routine for the shapes you wanted,鈥� he recalls.

To make the objects themselves, he focused two UV lights on a vat of liquid plastic and used two motors to guide the light across its surface, solidifying a sliver of plastic into a flat shape. The third motor then lowered the solidified piece, submerging it in liquid plastic again, ready to add the next layer.

At first, Hull struggled to get the layers to stick and the shapes to hold together. 鈥淚 made lots of junk,鈥� he says.

Night after night he persevered. Slowly the shapes improved, until he finally made something he had designed 鈥� though considering what 3D printers can make now it was a modest triumph.

鈥淭he first actual part I made was just a small cup shape.鈥� But it was enough. The idea was ready to take to the next level. 鈥淲e got the patent application in and our patent attorney was all excited. He thought it could be a real breakthrough. A number of the engineers in the company were excited about it too.鈥� Hull was soon back in his boss鈥檚 office again, pushing his idea. It was time for the company to commercialise stereolithography, he said.

It didn鈥檛 fly. Pressing ahead would mean a big investment in time and resources, and his boss decided it wasn鈥檛 worth the risk.

It was probably the right decision, albeit for the wrong reasons. What neither of them knew at the time was that somebody had got there before them. Just three weeks earlier, a team at the French General Electric Company led by Alain Le M茅haut茅 had filed a patent for virtually the same process.

鈥淲hen you鈥檙e trying to do something new, very few people see the wisdom of it鈥�

With no patent and no backing, Hull鈥檚 dream was over. He can be philosophical about it now. 鈥淭he history of technology tells you that when somebody invents something, you can be pretty sure somebody else in the world is close to it too,鈥� Hull says.

But coming first is not the same as winning. Le M茅haut茅鈥檚 bosses turned out to be even more risk-averse than his. The General Electric Company abandoned the patent application, seeing no potential in it. Hull鈥檚 patent was approved and he decided to go it alone. In 1986 he set up his own company, 3D Systems.鈥漌hen you鈥檙e trying to do something new, very few people see the wisdom of it,鈥� Hull says. 鈥淏ut I鈥檓 a pretty positive person. I鈥檇 hear all the naysayers and it wouldn鈥檛 affect me.鈥�

The first people to see the potential were automobile manufacturers, who at the time were lagging badly behind their Japanese rivals. 鈥淭hey were really enthused about what the technology could do for their company, and so we were soon making equipment, training them in how to use it and install it.鈥�

Since then, 3D printing has grown and grown. Several methods have been invented, and 3D scanners make it possible to recreate an object exactly. Apps are being developed that will let you scan an item with . And it鈥檚 not just for plastic any more 鈥� the technology has been adapted for all kinds of materials, even chocolate. Last year, private exploration company SpaceX used 3D printing to build a rocket engine. Perhaps the most impressive material, though, is human cells. It is now possible to print replacement blood vessels, skin and heart tissue, and 3D-printed organs are undergoing their first clinical trials. It鈥檚 a long way from the small cup Hull printed 33 years ago.

This article appeared in print under the headline 鈥淭he day the world became 3D鈥�