A boundary line of manufacturing history cuts across the factory floor of Siemens Hearing Instruments in Piscataway, NJ. On one side, skilled technicians use casting techniques, precision tools, and years of experience to craft the acrylic shells of hearing aids modeled from silicone impressions of actual ear canals.

On the other side of the factory floor, two pizza-oven-sized machines create similar shells from nylon dust. Inside the machines, needles of laser light, guided by digital design files, robotically scan back and forth, cinching paper-thin layers of dust into tough strata of plastic. Four hours and several hundred laser sweeps later, a batch of 80 hearing-aid shells is completed (see "From Dust to Hearing Aids," bottom). The process saves hours of human labor and produces hearing aids that fit and sound better than traditional ones.

It works so well that Siemens, the world's largest maker of hearing aids, is completely switching to the technology at several factories. "This whole process allows us to be more accurate and eliminate human error. This is going to change the business," says William Lesiecki, director of software and e-business solutions for Siemens Hearing Instruments.