A 3D construction system for creating an object includes, among other components, an online 3D blueprint model for the object and a 3D print head. An online control plan for controlling operation of the 3D print head to create the object according to the online 3D blueprint model is also provided. At least one 3D perception sensor scans a constructed portion of the object to generate sensor readings. A processing device, which is part of a computer system, creates an online 3D replica model of the constructed portion of the object using the sensor readings, and compares the online 3D replica model to the online 3D blueprint model or an ideal printed 3D model to identify a difference. The online control plan is modified responsive to the difference.