Structural optimisation and lightweight construction are closely interrelated: Lightweight construction is an element of structural optimisation. Nature follows this principle rather ‘naturally’ and therefore comprises a plethora of lightweight structures. However, technical implementations are characterized by different premises and contexts than natural occurrences. Yet, the principle in question is of outstanding significance in all of these fields. Plastics are highly suitable for lightweight construction. They have a low dead weight, and some plastics combine this characteristic with high stiffness. For these reasons, plastics particularly find use in the high-tech disciplines of aerospace, naval, automotive, and civil engineering. However, they may also find intelligent and economic use in building construction: saving material means reducing costs and preserving resources.