In the 1936 film Modern Times, Charlie Chaplin plays a factory worker whose only job is to tighten two bolts--again and again, all day, until he finally goes mad. That model is reaching its own breaking point, says German industrial giant Siemens, because it's too clunky to keep up with market demands. "We're going to see more complex products that consumers or different industries want us to manufacture," says Livio Dalloro, head of research for Siemens Corporate Technology. "The costs to bring [an assembly line] up and then essentially bring this down, when you are going to be switching to a different product, are pretty high." In other words, the costs of reconfiguring a traditional production line for a new product get in the way of being able to quickly iterate on product design.

That said, current technology won't allow us to make anything larger than the printing machines themselves. Some smart people have suggested that we should look to nature to see how it builds things--specifically, spiders, and the way they can swarm together to build massive nests for themselves. Siemens, the German engineering and telecommunications company, has taken this concept to heart. A team of researchers at its Princeton, New Jersey, laboratory are creating autonomous spider-like robots that can work together to 3D-print structures on command. While Siemens isn't known for its robotics research, Livio Dalloro, the head of the company's "Product Design, Simulation & Modeling Research" group in Princeton, said in an interview that the company views the bots as a "moonshot."

If you're afraid of spiders, then you might find Siemens's vision for future manufacturing lines a bit alarming. In a lab in Princeton, New Jersey, the company's researchers are testing spider-like robots that extrude not silk but plastic, thanks to portable 3-D printers. The robots can work together autonomously to create simple objects. The work is at an early stage, but it hints at where manufacturing may be headed, thanks to more sophisticated robot hardware, smarter control software, and new ways of forming components using 3-D printing. Unlike a conventional robotic production line, which has to be carefully reconfigured for each new product, a team of mobile manufacturing bots would simply be given the latest design and left to go to work. Livio Dalloro, head of product design, modeling, and simulation at Siemens, says that the robots (which, unlike actual spiders, have only six legs) can currently produce only very simple objects, like cubes, but the idea is that they would eventually clamber around a larger, more complex object, building it as they go.