What about accuracy?

As for the accuracy of the printed models, RP tolerances aren't as good as what's available with plastic injection molding, explained RP consultant Todd Grimm, president of T. A. Grimm & Associates. But they can be better than investment casting, which is used to make items such as golf clubs and other metal items that will be subjected to further finishing, he added.

Tolerances for high-end RP machine are usually 0.1 per cent or 0.2 per cent, said John Kawola, vice president at Z Corp.

With low-end 3-D printers, tolerances are rarely less than 0.5 per cent. "But with, say, an engine block, you don't care about the tolerances except for the holes, and you machine-finish those anyway," Kawola said. "3-D printing probably satisfies 70 per cent to 90 per cent of what people want to do with a prototype." Consequently, sales of 3-D printers have been growing by 30 per cent to 40 per cent yearly for several years and now amount to 80% of the whole RP market, Kawola said.

"It speeds up the design process by at least a factor of four," estimated 3-D printing user William Effrece, lab manager at The Stanley Works tool factory. "Previously, making a prototype was something done only at the end of the design process, it cost $3,000, and you had to wait two or three weeks. Now it can be done in a day, and the only expense is the cost of the materials. Our machine paid for itself in three months." He uses a 3-D printer from Z Corp., whose powder-deposition model-building technology allows for photorealistic models.

Make your own toys

But wouldn't customers of companies such as FigurePrints be happier if they were able to print their figurines at home -- as well as appliance replacement parts, toys, ornaments, kitchenware, etc?

One company hoping to meet this potential demand is Desktop Factory in California. It's taking advance orders for a US$4,995 system to be delivered sometime later this year.

"I see the low-cost availability of 3-D printing as having major implications," said Cathy Lewis, CEO of Desktop Factory. She anticipates the system being popular with schools and hopes it will promote the education of a new generation of US engineers.

"But the long-term vision is rapid manufacturing in the home," Lewis said. "You have the ability to create one-off products and customized toys. Instead of importing items by millions from China, transporting them to warehouses and then stores, where we drive to pick them up, you will download a legal file, for a legal fee, and print your own repair part. Our parts are durable enough to serve as end-user items."

She anticipates that the "cost of goods" to create a Desktop Factory unit will fall to US$500 by late 2011. "So in 2012, I should be able to sell it for US$1,000," she said. But she also wants to see more low-end software tools become available. She and others pointed to Google's SketchUp 3-D design package, available as a free download, as an example of what would be needed. Lewis said that the Desktop Factory unit may eventually have an interface for SketchUp files. (Professional 3-D CAD tools can cost thousands of dollars.)

As for the Desktop Factory system, which involves plastic and metal powder heated with a halogen light, "in terms of accuracy, they have some work to do," said Michael Berman, chief technology officer at the Art Center College of Design in Pasadena.

Berman tested a Desktop Factory beta unit for three months. "If you were doing a doll, an expensive 3-D printer would produce something like a manufactured doll you'd get in a store, whereas from this unit, the eyebrows would not be sharp, and a mouth would lack a sharp edge -- like a photo a little out of focus. But obviously it's a much lower price point, and we are enthusiastic about it."