behavior of structures found in nature. Several biomaterials such as bones, shark teeth, [16] seashells, [17,18] ladybug legs, [19] woodpecker beaks, [20] kingfisher beaks, [21] and many others have highly controlled structures in different length scales, from submicrometer to macrometer scale have been explored recently. These studies clarified the correlation between the complex architecture of these structures and the observed mechanical performance. The functional geometric design of natural materials can be used to render high-performance advanced materials.Mimicking natural structures is always challenging due to the lack of appropriate synthesis methods. However, recent advances in additive manufacturing technology (such as 3D printing) opens new pathways for building complex structures, which remain inaccessible using conventional methods. [22][23][24][25] Important results on biomimetic structures with 3D printers to determine the role of geometry on structural mechanical behavior have been recently reported. [26][27][28][29][30] Another study using 3D printing of complex structures called Schwarzites explained how unusual mechanical behavior at the atomic scale is translated into macroscopic properties, which can be scalable to other length scales. [31] Lightweight materials with high ballistic impact resistance and load-bearing capabilities are regarded as a holy grail in materials design. Nature builds these complementary properties into materials using soft organic materials with optimized, complex geometries. Here, the compressive deformation and ballistic impact properties of three different 3D printed polymer structures, named tubulanes, are reported, which are the architectural analogues of cross-linked carbon nanotubes. The results show that macroscopic tubulanes are remarkable high load-bearing, hypervelocity impact-resistant lightweight structures. They exhibit a lamellar deformation mechanism, arising from the tubulane ordered pore structure, manifested across multiple length scales from nano to macro dimensions. This approach of using complex geometries inspired by atomic and nanoscale models to generate macroscale printed structures allows innovative morphological engineering of materials with tunable mechanical responses.

This cover shows Tubulane structures made up of bio‐degradable soft polymer created by 3D printing. It can handle ballistic impact. The bullet stops in the second layer of the tubulane structure with no significant structural damage while bullet fire with the same speed propagates the crack through the whole reference cube. More details can be found in article number 1904747 by Douglas S. Galvão, Chandra Sekhar Tiwary, Pulickel M. Ajayan, and co‐workers.