The design or model protects the appearance of a product as it appears to the eye, e.g. as defined by its lines, contours, colors, shape or form. It does not protect the functional aspects, that is those who play a purely technical function.
The Design patent therefore protects an ornamental or aesthetic feature of a functional element, a feature that can relate to a 3D entity as the silhouette of a car, or to a 2D drawing as a mosaic or a geometric pattern.
As examples of validly registrable designs we can mention: