SAN MATEO, Calif. — Invisalign, a San Jose company, uses 3-D printing to make each mouthful of customized, transparent braces. Mackenzies Chocolates, a confectioner in Santa Cruz, uses a 3-D printer to pump out chocolate molds. And earlier this year, Cornell University researchers used a 3-D printer, along with injections of a special collagen gel, to create a human-shaped ear.
The machines, generally the size of a microwave oven and costing $400 to more than $500,000, extrude layer upon layer of plastics or other materials, including metal, to create 3-D objects with moving parts. Sales are booming, with a projected jump from about $1.7 billion in 2011 to $3.7 billion in 2015.
Experts warn this innovation could turn controversial — because of safety concerns about what users make, and the impact on manufacturing-dependent countries.