As the capabilities of 3-D printers have grown, so have news of their achievements. Three innovators explain what's still beyond their capabilities--for now.
Printed by Cody Wilson; cofounder, Defense Distributed
"All these experts were saying, 'This isn't possible.' I was doing basic math and saying, 'Hm, it kind of does seem possible.' It was a materials problem."
Still Out of Reach: Shotgun
"A shotgun shell has a brass case at the back, but really it's just plastic. When you send a spark through it, it's like blowing up a bomb."
Printed by Hod Lipson; cofounder, Fab@Home at Cornell University
Achieved: Pink cube of milk
"We can take basic food additives and combine them to create new foods, but it's not something people eagerly embrace. It's too strange."
Still Out of Reach: Bacon
"If familiar foods aren't exactly real--the marbling, the color--you immediately become suspicious. It's technically possible to do it, but not right now."
Printed by Andrew Dawood; founder, Digits2Widgets; dentist
"I use 3-D printing to make implants for the jaws, or for cranioplasties. It is the only way that you can make these complex structures."
Still Out of Reach: Heart
"We're looking at printing scaffolds, into which cells will grow. What we need are the growth factors and metagenic proteins to stimulate that."
[Jay Janner/AP Photo/Austin American Statesman (gun)]