Abstract Reconstructing a 3D sampled object into a computerized model is an essential part of reverse engineering. Applications such as casting and injection molding, however, also require a more abstract mid-surface representation for analysis. Reconstructing a mid-surface from a thin object is known to be difficult and time consuming. In this paper, a reverse engineering method is proposed for simultaneously reconstructing a 3D object and its mid-surface. The object and the mid-surface models are created so that their mutual relations enable subsequent interactions between design and analysis, needed according to simulation results. The stages in modeling the reverse engineering object and its mid-surface are: (1) sampling and filtering points through a data reduction algorithm; (2) recognizing dominant pairs of boundaries; (3) parametrizing object boundaries and finding parametric correlations between them, according to mid-surface definition; and (4) reconstructing a 3D object and its mid-surface. Error analysis, results and examples will be demonstrated.