Architectured materials have emerged as a new materials design strategy for exploring new lightweight materials. Nature itself offers inspiration, as exemplified by the remarkable structural arrangements and mechanical properties found in shells. Recent studies have demonstrated that a smart structural designs in combination with a specific selection of materials can result in exceptional mechanical properties at low relative densities.

In our research, we delved into the structural composition of shells to develop strong yet lightweight materials. Shells, composed of carbonate mineral units embedded in a polymeric matrix, served as our inspiration. Our efforts concentrated on reproducing mechanically robust polymer architectures as an initial step towards creating architectured mineralized composites. Two distinct  geometries were explored integrating different honeycomb-type unit cell arrangements. The fabrication process involved layer-by-layer projection-micro-stereolithography, with a lateral resolution of approximately 2 µm and a build height resolution of around 10 µm. In addition, pore-containing samples were fabricated to facilitate subsequent mineralization mimicking the structure of the shells. The resulting samples, with an overall size of about one cm, underwent thorough examination through light and scanning electron microscopy. Mechanical characterization was carried out through uniaxial compression tests using a microindenter.

The properties of the material and of the printed structures were investigated. A distinct mechanical response of the different types of honeycomb architectures was observed. While, as expected, for a hexagonal unit cell highly anisotropic behavior was observed with the highest strength values observed along the building direction (z-axis), a curved unit cell design exhibited similar strengths values but revealed three different behaviors depending on the loading direction. The introduction of pores did not result in a lower strength in all cases. The weakening effect depended on both the pore size and the loading direction of the architectures. These architectures serve as excellent foundations for customizing mechanical properties to suitmeet the requirements of diverse loading scenarios.