1. A computer-implemented method of automatically adding constraints between entities in a subject computer-aided design (CAD) model of a real-world object, the method comprising: storing information regarding CAD model entities and related constraints in a computer database, wherein the CAD model entities belong to one or more components of at least one of the subject CAD model and other CAD models; for one CAD model entity of a given component that is one of to be added to and in the subject CAD model, accessing the computer database to determine constraints that have been previously used for at least the one CAD model entity of the given component, the determined constraints having been previously used in at least one of the subject CAD model and the other CAD models; and automatically adding to the subject CAD model a new constraint between at least the one CAD model entity of the given component and another entity in the subject CAD model based on the previously used constraints.