  Biological systems evolve with minimum metabolic costs and use common
components, and they represent guideposts toward a paradigm of manufacturing
that is centered on minimum energy, local resources, and ecological
integration. Here, a new method of metalworking that uses chitosan from the
arthropod cuticle to aggregate colloidal suspensions of different metals into
solid ultra-low-binder-content composites is demonstrated. These composites,
which can contain more than 99.5% metal, simultaneously show bonding affinity
for biological components and metallic characteristics, such as electrical
conductivity. This approach stands in contrast with existing metalworking
methods, taking place at ambient temperature and pressure, and being driven by
water exchange. Furthermore, all the nonmetallic components involved are
metabolized in large amounts in every ecosystem. Under these conditions, the
composites' ability to be printed and cast into functional shapes with metallic
characteristics is demonstrated. The affinity of chitometallic composites for
other biological components also allows them to infuse metallic characteristics
into other biomaterials. The findings and robust manufacturing examples go well
beyond basic demonstrations and offer a generalizable new approach to
metalworking. The potential for a paradigm shift toward biomaterials based on
their unique characteristics and the principles of their manufacturing methods
is highlighted.
