Researchers at Pittsburgh, Pennsylvania's Carnegie Mellon University (CMU) successfully use a 3-D printer (specifically, a fused deposition modeling (FDM) printer) to produce hair-like strands, inspired by the use of a hot glue gun to produce gossamer strands. Also, using certain materials (like collagens, alginates, and fibrins), with a 3-D printer and special bioprinting techniques, another team at CMU produced human coronary arteries and small, embryonic-like human hearts.