A US surgeon has met the need for prosthetic hands in children by creating them on a 3D printer for about $20.

When trauma surgeon Albert Chi gave a talk last year about advanced prosthetics and was asked what was easy, available and affordable, he was stumped.

So he began to hunt for more basic options.

He turned to the 3-D printer, one his wife bought him for Father's Day and with sheets of coloured plastic, free designs and advice found online, he made a hand for about $US20 ($A21).

"One of the first kids we fitted was a 2-year-old," Chi said.

"We thought the child was too young. But we weren't even able to finish strapping it on and the kid was picking an object up."

The need for such prosthetics has spawned a network of volunteer designers, medical workers, artists, engineers, parents and 3-D print enthusiasts who have been outfitting children with prosthetics - some with lower-end machines that cost less than $1,000.

The 3-D printed prosthetics are particularly useful for children. They often grow out of prosthetics and can't afford replacements every few months or years. The 3-D versions also can be lighter and easier to wield - and come in their favourite colours.

The US Centers for Disease Control and Prevention reports that four in 10,000 children are born with some congenital hand loss or about 1,500 a year. That doesn't include those who lose their hands in accidents.

Insurance also doesn't always cover paediatric prosthetics, which cost up to $40,000, said Chi.

And children can have trouble adjusting to them.

Griffin Matuszek, who was born without part of his left hand, found his traditional prosthetic mostly useless and a bit scary, said his mother, Quinn Cassidy.

So she began researching alternatives and when 5-year-old Griffin was to be fitted with one of Chi's hands, he requested one that glowed in the dark.

Cassidy said Griffin was drawn to his new hand because he could put it on himself and easily manipulate it with his palm muscles. The traditional prosthetic was tight and covered his forearm.

"He put it on and immediately gave Dr Chi a high five and then gave everyone in the room a high five," Cassidy said.

"He was able to pick up a small ball and throw it with his left hand right away."

Another recipient was Mike Waldron, 22, a senior political science major, at the University of Maryland, Baltimore County.

"It gives me many options. I can go kayaking and work on my cars now," said Waldron, who said an electronic prosthetic device could cost as much as $40,000, while the one he received at Hopkins, was in the $45 range.

"It's all plastic and the only metal is the screws. The string is 40-pound test fishing line."

The printers work like glue guns, as plastic sheets are fed into the machines and melted. The plastic comes out in layers that eventually look like Lego pieces, fitted together with plastic bolts that also are printed.

Hand parts take up to 10 hours to print and another couple of hours to assemble with elastic cords to keep the hands open. Kids make them grasp by flexing their palms or wrists. Extra cords can be used to strap them on kids with more extensive limb loss.

Chi, a trauma surgeon at Johns Hopkins Hospital, called the effort a "labour of love."

Copyright AAP 2014