Richard Van As was working in his home near Johannesburg, South Africa, in May of 2011, when he lost control of his table saw, NPR reports. “It’s a possibility that it was a lack of concentration,” he says. “It’s just that the inevitable happened.” The carpenter lost two fingers and mangled two more on his right hand. While still in the hospital, he was determined to find a way to get back to work. Eventually, solving his own problem led him to work with a stranger on the other side of the world to create a mechanical hand using . Other prosthetics, including a lower jaw, have been made with the technology before, but making a hand is particularly tricky…