"It's going to start slow—people will make toys for their kids and so on," she predicts. But soon, people will be printing out increasingly sophisticated products, from home goods to shoes.

One big problem with 3-D printing in its current form, said Benyus, is that many of the printers rely on toxic building materials, in the form of an increasing array of polymers (plastics), resins, and metal powders.

"Some 'makers' [3-D printer users] are starting to see their skin reacting, and when you look at the material data safety sheets for these materials you see serious warnings," said Benyus. That's a concern, because people are using the printers in their homes and inhaling the fumes, she said.

"We shouldn't have to wash our