A mathematical technique for representing solid objects. Unlike wireframe and surface modeling, solid modeling systems ensure that all surfaces meet properly and that the object is geometrically correct. Solid models allow for interference checking, which tests to see if two or more objects occupy the same space.

Solid modeling is the most complicated of the CAD technologies, because it simulates an object internally and externally. Solid models can be sectioned (cut open) to reveal their internal features, and they can be stress tested as if they were physical entities in the real world. See tessellation. See also 3D printing.