1. A system comprising: one or more computer storage media having instructions stored thereon; and one or more data processing apparatus configured to execute the instructions to perform operations comprising (i) receiving input specifying different material properties of an object to be manufactured, (ii) generating from the input a three dimensional (3D) model of the object using overlapping volume representations of the different material properties of the object, wherein the overlapping volume representations employ different data formats and different resolutions, and (iii) storing the 3D model of the object for use in manufacturing the object.