Clause 71

The copyright in an artistic work is not infringed by the making of a later artistic work by the same author if, in making the later work, the author does not repeat or imitate the main design of the earlier work.

Subsection (1) shall have effect notwithstanding that part of the earlier work is reproduced in the later work and that, in reproducing the later work, the author used a mould, cast, sketch, plan, model or study made for the purposes of the earlier work.