Being born without fingers can be tough for any child. Getting new ones -especially red and blue super hero themed digits -has made 8-year-old Kaori Misue a vibrant playground star.

Flexing her wrist muscles to bend the plastic fingers, she can work with tape and stickers at an arts and crafts class. She can ride a bike, skip a rope and bake pastries with her mom. Her amazed friends have even begged to borrow the 3D printed hand, which looks a little like a cheerily colored Transformers toy strapped to her wrist. “It was magical,” her mom, Karina Misue, said. “The confidence it gives kids is tremendous. They’re using it with pride.”

Hundreds of Argentine kids like Kaori who were born without limbs are now able to write, play sports and make music thanks to low-cost prosthetic hands devised by Gino Tubaro, a 21-year-old inventor whose work was praised by President Barack Obama during a visit to Argentina last year.

Tubaro’s “Limbs” project is part of a trend of open-source 3D printing technology initiatives around the world.

Today, more than 500 people, mostly children, have received similar prostheses and 4,500 more remain on a waiting list. Basic designs are custom modified to fit the needs of each user with the help of orthopedists.

The project uses volunteers around the world who own 3D printers to print the pieces and assemble and deliver the hands. They can cost as little as $15 compared to sophisticated designs that are priced up to $15,000.Some of the pieces can be interchanged to fit a specific purpose: from playing pingpong to grabbing a fork or riding a bike. If children outgrow a model, it can be easily replaced, perhaps with a different theme.

“It’s a wonderful experience because we’re getting photos of kids… doing things that they couldn’t do before,” Tubaro said.