Inspired by the fact that nature provides multifunctional composites by using universal building blocks, the authors design and test synthetic composites with a pattern inspired by the microstructure of cortical bone. Using a high-resolution multimaterial 3D printer, the authors are able to manufacture samples and investigate their fracture behavior in mechanical tests. The authors’ results demonstrate that the bone-inspired design is critical for toughness amplification and balance with material strength. The failure modes of the authors’ synthetic composites show similarities with the cortical bone, like crack deflection and branching, constrained microcracking, and fibril bridging. The authors’ results confirm that our design is eligible...