Three-dimensional (3D) printers; 3D bioprinters for fabrication of living tissue models; computerized machines for the generation of 3D shaped parts; machines for manufacturing 3D models, namely, computer-aided modeling devices; computer- aided additive machines for manufacturing 3D objects; machines for manufacturing 3D models, namely, computer-aided modeling devices and associated computer hardware and software sold as a unit; computer-aided additive machines for manufacturing 3D objects and associated computer hardware and software sold as a unit; machines for manufacturing 3D living tissues; machines, namely, 3D bioprinters for the printing of living tissues; cartridges sold empty for containing printing material for use with 3D printers and 3D bioprinters; cartridges sold empty for containing bioprinting material for use with 3D printers and 3D bioprinters; printing cartridges sold empty for containing biomaterial for use with 3D printers and 3D bioprinters; printing cartridges sold empty for containing bioink for use with 3D printers and 3D bioprinters; 3D printers, namely, bioprinters using extrusion-based bioprinting methods