Cellular structures are highly porous metamaterials. They are common building blocks in natural systems, as seen in bones and shells, offering lightweight and high strength.  The mechanical properties of these truss-based structures, however, heavily rely on the underlying cellular geometries. Often times, the cellular structures are brittle. When coating a thin shell on the cellular structure, forming a continuous minimal surface, a shellular structure of different curvatures is formed, of which the toughness could be dramatically improved. Through the design of various 3D printed cellular structures with varying subdivided cell densities and coating materials, we explore the effect of geometry and materiality, and their combination to the mechanical performance and optical functions of the shellular structures. The 3D shellular structures have potential applications such as impact energy absorber, stress sensor, and high strength and lightweight structural materials.