EmmaLavelle is a little girl from Delaware who was born in February 2008 with a rare condition that left her able to move only one part of her body: her thumbs. Doctors told her parents Megan andAndrew thatEmma had a severe form of arthrogryposis multiplex congenita a condition afflicting one in 3 000 live births. Surgery and occupational therapy helpedEmma develop use of most of her body but by the time she was two her arms still hung limply at her sides; her weak biceps simply could not overcome the force of gravity. Her parents learned of a prosthetic device developed at the nearby Nemours/Alfred I. duPont Hospital for Children in Wilmington that could help: a metal exoskeleton that supports the patient’s arms enabling his brain to direct movement. The catch: the device had never before been used with someoneEmma’s age. Besides being too heavy for her tiny limbs the device cost tens of thousands of dollars; each metal component had to be custom-manufactured and since she would be growing it would mean she’d have to be fitted with a completely new set every few years. “She required something light and small that would go with her body ” saidTariqRahman head of pediatric engineering and research at Nemours. As it happened the hospital already had the solution on its premises: a three-dimensional printer called the Stratasys Dimension 3D. Using scans of Emma’s body and existing CAD design software Rahman and his team were able to feed a file to the 3-D printer that directed it to produce lightweight durable plastic prosthetics custom-fit for the patient’s little arms. And instead of costing in the tens of thousands of dollars Emma’s device cost just tens. Of course the first timeEmma wrapped her arms around her mother in a tender embrace chances are that the cost was not the topmost concern in their minds.Emma’s story is just one of many that has come to light in recent years raising public awareness of the new field of 3-D printing. The technology has already demonstrated a seemingly endless array of practical applications and the full implications of its versatility are only just beginning to be felt. Three-dimensional printers are used in manufacturing large items like airplane engine parts and can also be called on to produce items as simple as a door handle a belt or a wrench. The market is large and only growing. Estimates at the high end peg the 3-D printing market at $20 billion by 2020 as much as five times its current size. Stratasys the brand name behind the device that madeEmma’s prosthesis just closed the books on 2014 with total revenues of $750.4 million representing a 54 percent increase over the $486.7 million for the same period in 2013.