Abstract: A method and apparatus for forming a three-dimensional object by thermal spraying utilizes a plurality of masks positioned and removed over a work surface in accordance with a predetermined sequence. The masks correspond to cross sections normal to a centerline through the workpiece. One set of masks defines all cross sections through the workpiece. A second set of masks contains at least one masks which corresponds to each mask of the first set. Masks from each set are alternatively placed above a work surface and sprayed with either a deposition material from which the workpiece will be made or a complementary material. In this manner, layers of material form a block of deposition material and complementary material. Then, the complementary material which serves as a support structure during forming is removed. Preferably, the complementary material has a lower melting temperature than the deposition material and is removed by heating the block.