A new design model for the creation of mechanical components has been developed. In this model, the shape is expressed by its areas of prominence or maximum curvature, for which we use the term pseudoedges. In terms of traditional design, these represent both fillet, chamfer and intersection lines, and more general shape features. The pseudoedges of the model combine with a skeletal shape that is used as a starting form, thereby creating a hierarchy of geometric dependencies that affords both global and local control. The surface is represented by a quilt of parametric Bezier patches, with tangent plane continuity everywhere and only certain isolated singularities. Considerable degrees of deformation are possible, with predictable control and at small computational expense; there is no need for computation of intersections or parameter space trimming of patches.