Solid modelers have become commonplace in engineering departments in the last ten years due to faster PCs and competitive software pricing.

Solid modeling software creates a virtual 3D representation of components for machine design and analysis. Interface with the human operator includes programmable macros, keyboard shortcuts and dynamic model manipulation. The ability to dynamically re-orient the model, in real-time shaded 3-D, is emphasized and helps the designer maintain a mental 3-D image.

A solid part model generally consists of a group of features, added one at a time, until the model is complete. Engineering solid models are built mostly with sketcher-based features; 2-D sketches that are swept along a path to become 3-D. These may be cuts, or extrusions for example.

Design work on components is usually done within context of the whole product using assembly modeling methods. An assembly model incorporates references to individual part models that comprise the product.

Another type of modeling technique is ‘surfacing’ (Freeform surface modeling). Here, surfaces are defined, trimmed and merged, and filled to make solid. The surfaces are usually defined with datum curves in space and a variety of complex commands. Surfacing is more difficult, but better applicable to some manufacturing techniques, like injection molding. Solid models for injection molded parts usually have both surfacing and sketcher based features.
Engineering drawings are created semi-automatically and reference the solid models.