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Solid primitives are the simplest solids used in CSG. As shown in Figure 2.29, most commonly used primitives include cuboids, cylinders, prisms, spheres, cones, and tori. Note that different solid modelling tools may use different solid primitives in CSG.

Figure 2.29 Examples of solid primitives. (a) Cuboid. (b) Rectangle cuboid. (c) Prism. (d) Sphere. (e) Tapped cylinder. (f) Cylinder. (g) Cone. (h) Torus.

For an object with a complex geometry, solid primitives can be customized. Table 2.11 lists some common methods used to create solid primitives (i.e. design features) in a solid modelling tool. These modelling tools include extruding, revolving, sweeping, lofting, and many others.

Table 2.11 Modelling tools for customized solid primitives.

Modelling tool	Explanation	Example
Extruding	Extruding creates a solid by moving a two‐dimensional profile along a straight path.
Revolving	Revolving creates a solid by revolving a two‐dimensional profile along an axis.
Sweeping	Sweeping creates a solid by translating a 2D profile along a 3D path with or without one or a few of 3D guide curves.
Lofting	Lofting creates a solid by specifying and connecting vertices on a series of 2D profiles.