1. A computer implemented method of automatically specifying design rules for a digitally controlled manufacturing process, said method performed by the computer comprising the steps of: providing a training set of 3D point meshes that digitally represent an anatomical structure, wherein each mesh comprises a set of 3D points with an associated intensity value; for each 3D point mesh, finding groupings of the points that define clusters for each shape class of a plurality of classes that define said anatomical structure; calculating a prototype for each shape class cluster; and associating one or more design rules with each shape class prototype, wherein said design rules specify a design strategy for an object that fits said anatomical structure.