Methods and apparatus associated with three-dimensional objects are described. In an example, a method comprises receiving data representing a three-dimensional model object, the data comprising object model data and object property data. For at least one object property, a sub-region of the object in which the object property is non-variable is identified and, for at least one location within the object, all sub-regions in which the location is situated are identified. Based on the combination of identified sub-regions for a location, print material data is determined for the location. Control data for the production of a three-dimensional object is generated according to the print material data.