4. Design parts to be multi-functional. Multi-functional parts reduce the total number of parts in a
design, thus, obtaining the benefits given in rule 1. Some examples are a part to act as both an electric
conductor and as a structural member, or as a heat dissipating element and as a structural member. Also,
there can be elements that besides their principal function have guiding, aligning, or self-fixturing features
to facilitate assembly, and/or reflective surfaces to facilitate inspection, etc.