Accessories for 3D printers used for making 3D objects by additive material deposition, namely, print heads for 3D printers; software for operating and controlling 3D printers; software for use in receiving and manipulating 3D model file data for fabrication of 3D objects on a 3D printer; software used for transmission of 3D file data for printing on a networked 3D printer; software for operating and monitoring a network of 3D printers; software for use in analyzing 3D model geometry, additiv...