Constructive Solid Geometry (Csg or C-Rep):
CSG model is depend on the topological notion that a physical project object may be divided in a set of primitives that may be combined in a certain order following a set of rules to form the object. The basic solid primitives are following: blocks, cones, spheres, cylinders, tubes, and hexahedras, as illustrated in Figure.
Figure: Solid Modeling Entitie