Since its early days, geometrical reconstruction (GR) has been developed as a stand-alone process for reconstructing a 3D CAD model from a 2D engineering drawing. Addressed in this paper is an attempt to extend GR application to interface it with the rapid prototyping process (RP) in order to construct a prototype directly from an engineering drawing. A layer-based geometric reconstruction (LBGR) concept has been developed to couple the two applications. LBGR locally translates information on the 2D drawing into a stack of contours section-by-section in a top-down direction, in which the top and bottom contours of each section are identified before its intermediate contours are generated. It can be applied to parts that consist of regular surfaces whose edges are clearly presented on the orthographic views (e.g. plane surfaces, conical surfaces, ruled surfaces with cross-sectional contours parallel with the xy plane). This concept has been implemented in LabVIEW to demonstrate this direct interface. Inputs and outputs are orthographic view images of a drawing and the vector files of contours, respectively. The direct transformation of mechanical part drawings into physical prototypes is also presented in this paper.