Although the models shown in these pages are approximations to regular shapes, models of arbitrary shape, if available as series of parallel cross-sections, can also be built by aggregations of cubes. The algorithm can also yield a file in which cubes, packing the interior of the surface. are written in a compact format. The results of our algorithms are very much like those of the well-known Marching Cubes program currently in use for the 3D viewing of CAT and MRI images. The images on the right and left are approximations of two surfaces of revolution, while the central one is an interior view of the approximation shown on the left.