What does copyright protect? (Courtesy SABS)
The following works, if they are original, qualify for copyright: Literary works, musical works, artistic works, cinematograph films, sound recordings, broadcasts, programme-carrying signals, published editions and computer programs.
The category of copyright works most relevant for product design will be artistic works. ‘Artistic work’ is defined to include drawings (including drawings of a technical nature or any diagram, map chart or plan), paintings, sculptures, engravings and photographs, all irrespective of their artistic quality; works of architecture; and works of craftsmanship (including works of artistic craftsmanship as well as works of craftsmanship of a technical nature). ‘Drawings’ would thus include engineering and industrial design drawings. The concept ‘works of craftsmanship’ would include three-dimensional articles, for example prototypes and models prepared in the course of design work.
In the case of your artistic works, a person who makes a three-dimensional reproduction (eg in the form of a usable article) of your two-dimensional artistic work such as a drawing, infringes your copyright in that drawing. This may also include the making of a two-dimensional reproduction of your three-dimensional work.
It is important to remember that copyright does not protect the underlying concepts of a design, only the particular rendition of it, which you have reduced to material form (including in a computer).