Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for identifying a plurality of part families, where each part family comprises a plurality of parts; and for each part in each part family: obtaining connection port geometry information for a physical part in a part family; positioning each of the port vectors in a three-dimensional space at a respective location specified by the port vector; generating a respective port alignment line for each of the port vectors; generating one or more base curves each positioned to align with a plurality of the port alignment lines; generating one or more port solids from the connection port geometry information; and constructing body geometry between each of the one or more port solids by sweeping along a respective base curve, wherein the constructing is based at least on the connection port geometry information.