enlarge/ as the technology has improved, 3d printing has become a more realistic option for medical professionals, though printing a femur replica (seen here) presents much less of a challenge than creating a functioning prosthetic. getty imagesshare this storyfor people who are missing limbs, 3d printing can make new prosthetics—faster, cheaper, and better. for mosaic, ian birrell reports that this idea could transform mobility for millions around the world. this article was first published by mosaic and is republished here under a creative commons license.john nhial was barely a teenager when he was grabbed by a sudanese guerrilla army and forced to become a child soldier. he was made to endure weeks of walking with so little food and water that some of his fellow captives died. four more were killed one night in a wild-animal attack. then the boys were given military training that involved “running up to ten kilometres in the heat and hiding” before being given guns and se...