Architected metamaterials, a subset of hybrid materials, can offer multifunctionality through their tuneable architectures for a wide range of applications. Recently, multiple literature studies have independently shown that the introduction of aperiodicity (i.e. topological defects) in architected metamaterials can enhance damage tolerance, strength, and energy absorption. This behaviour imitates that of grain boundary structures in polycrystalline metals and is particularly attractive in the design and manufacturing of 3D printable orthopaedic implants. Thus far, a systematic mechanical investigation of this new class of metamaterials has not yet been conducted. In this study, we investigate 3D printed polymeric-mesoscopic 2D honeycomb structures and assess the role of a unique kind of topological defect consisting of a pentagon and heptagon pair (referred to as 5–7 defects) arranged to mimic dislocations found in graphene. Similar to a crystal where the accumulation of dislocations forms a grain boundary, here the arrangement of 5–7 defects forms a domain boundary (a “meta-grain boundary”). We designed a range of honeycomb bidomain structures with various arrangements of 5–7 defects creating domain boundaries based on different misorientation angles. These honeycomb structures were fabricated using additive manufacturing (Digital Light Processing DLP 3D printing) and subjected to mechanical testing (quasi-static in-plane compression). Finally, the confluence of experiments and finite element simulation demonstrated that the arrangement of the 5–7 defects has a significant impact on the properties and failure mechanism of the honeycomb bidomain structures.