In the past four years, designers of a variety of products, including shoes and cellphones, have been buying specialized office printers costing $20,000 to $50,000 that can quickly produce a plastic model using computer-aided-design, or CAD, software.
Though they resemble typical office copiers on the outside, these are not ink-on-paper printers. Rapid prototyping machines were pioneered by 3D Systems Corp., of Valencia, Calif., nearly 20 years ago. They work by taking computer-aided-design data and using it to build a device layer by layer. Inside a 3D printer, either a print head shoots out plastic particles and glue, or an ultraviolet or laser beam passes over a liquid resin bath, hardening a layer of plastic, 3/100ths of an inch thick, in a computer-generated shape. Then the machine builds layer upon layer until the full model is completed, one to four hours later.