We present an efficient and user-friendly parametric CAD-based design method for the graphical description of positive displacement machines, exploiting commercial parametric CAD software and a tailored interface. An executable module simulates the motion of the machine components, analyzes the machine geometry, and automatically extrapolates the geometrical data from the 3D CAD model, generating data files that can be directly used for following fluid dynamic analyses. The graphical approach supports investigation of the machine performance and exploring optimized design variants. The method has been applied to three industrial test cases: An external gear pump, an axial piston pump, and a gerotor pump. A complete case study focused on the external gear pump is proposed, as well as the results from the other two types are summarized. We validate the CAD-based method by comparing the obtained data with the data coming from the application of state-of-the-art analytical methods.