How can a printer save someone’s life? Doctors at a hospital in Gainesville, Florida, recently separated conjoined twin girls with the help of 3-D printing. According to Yahoo News, the twins, Scarlett and Savannah, each had their own complete set of organs but were attached at the liver, diaphragm, sternum and heart. To help the doctors prepare for the risky procedure, they created what they believe is the first-ever 3-D printed conjoined twin heart. The life-sized model allowed surgeons to examine the twins’ shared structures in the heart and practice the surgical separation itself.