Fused Deposition Modeling (FDM), an extrusion-based additive manufacturing (AM) process, enables the fabrication of lattice metamaterials with tailored mechanical properties. Despite its widespread use and technological advancements, the layer-by-layer deposition process introduces unavoidable geometric imperfections, which can significantly influence the mechanical and vibrational response of the printed components [1]. Besides, a comprehensive overview of the impact of such imperfections on the properties of lattice metamaterials is still lacking. This work focuses on 3D printed periodic lattices made of thermoplastic polyurethane (TPU) [2], exploring their potential for vibration control and wave attenuation. The study investigates how these features are affected by the presence of manufacturing-induced geometric imperfections, such as irregularities in node positions, cross-section variations and axis offsets [3]. A combined numerical–experimental approach is adopted [4] to assess how FDM specific defects affect dispersion relations and energy transmissibility. Preliminary results suggest that even small geometric deviations can lead to shifts in bandgap frequencies and modify the dynamic response, ultimately altering the wave-filtering capabilities of the metamaterial. This research aims to clarify how these deviations from the ideal configuration affect the mechanical response of the specimens and how they can be modeled and possibly exploited. The ultimate goal is to move beyond the conventional idea of perfect geometries, opening possibilities for innovative applications in engineering.