Modeling of curves and surfaces is an essential part of any CAD/CAM system. Once an accurate geometric representation of the design object has been obtained, it can be interrogated to verify the desired shape and performance. After interrogation, machine-tool paths can be generated, which can be used in numerically controlled machining for the production of the object. Afterwards, the quality of the manufactured product can be determined by comparing measured data to the design model. Praxiteles, an interactive system for modeling and manipulating free-form (or sculptured) curves and surfaces, has been developed to provide a process to eliminate undesirable shape features that may adversely affect the aesthetics and/or performance of the produced object. Praxiteles is the official US Navy software used for the inspection and exchange of marine propellers. The program and its documentation continue to be improved.