1. Apparatus for forming a three-dimensional object on a substantially cross-section by cross-section basis from a building material which is normally in a solid state and which is flowable when maintained at or above a flowable temperature, comprising: at least one computer programmed to convert data descriptive of a faceted representation of the object into data descriptive of object cross-sections; means for maintaining the building material at or above the flowable temperature thereby forming flowable building material; a dispenser responsive to the at least one computer for selectively dispensing successive layers of the flowable building material according to the data descriptive of object cross-sections; and a building environment which is maintained below the flowable temperature and into which the flowable building material is dispensed.