A system and method are provided for implementing control of the 3D printing of an object by a 3D printer. The method includes providing 3D printing apparatus comprising a controller and a 3D printing module. A digital print file (DPF) representative of the object to be printed, including layer by layer information, is provided to the printing apparatus and to the controller, details of objects pre-defined as subject to printing control are also provided to the controller. The digital print file is processed to provide a representation of the object to be printed which is then interrogated to determine whether there a possible match between the features of the object to be printed and features of an object predefined as subject to print control. Printing is interrupted if it is indicated that the object to be printed has been determined to show a possible match to features to an object pre-defined as subject to print control.