1. A method for designing, on a display device, a geometric shape, comprising the steps of: on a display device, displaying an initial set of similarly structured model exemplars, each exemplar including a first portion and a second portion; selecting a chosen set of models from the initial set of similarly structured model exemplars to apply to a model mix; mixing the set of models to form a currently displayed shape including a first portion and a second portion; on the display device, providing at least one selectable feature for manipulating the first portion of the currently displayed shape; and applying at least one constraint of the selectable feature to the currently displayed shape to update both the first portion and the second portion of the currently displayed shape into a new geometric shape design.