Researchers at Northwestern University have developed a hyperelastic biomaterial that can be quickly 3D printed in an endless variety of shapes and sizes, perfect for molding it to different body parts. The material is composed mostly of hydroxyapatite — a mineral form of calcium found in human teeth and bones — which was mixed with one of two polymers used in medicine and tissue engineering. Initial tests included bone grafts built with the material and implanted into mice, rats and one macaque that became integrated into tissue and stimulated bone growth without adverse effects.