One of the issues that modern implants face is their high stiffness, coupled with a positive Poisson’s ratio along the implant. This creates certain problems with bone inflammation and implant detachment. A possible solution to these problems is TiNi alloy lattice structure implants with low stiffness and negative Poisson’s ratio. This paper presents the results of simulation, fabrication by the SLM technique, and study of lattice structures with negative Poisson’s ratio, which can help to solve said problems. The studies involve the determination of mechanical characteristics, Poisson’s ratio, transformation temperatures, and the potential for a superelasticity effect of the lattice structure. The characteristics obtained at initial simulation were partially confirmed in the course of the works. Moreover, the possibility of fabricating TiNi alloy lattice structures with negative Poisson’s ratio (about −0.00323) and low Young’s modulus values (0.818 GPa) was confirmed by the SLM technique.

One of the most promising and innovative approaches in designing mechanical metamaterials for various applications is the use of bioinspired geometries. Nature offers a wide array of geometric forms and structures that have evolved to serve specific functions, including protection. Examples of such structures include the microstructure of pomelo peels and the geometry of starfruits (carambola), both of which are designed to protect the fruit from impact when falling from a height. Based on these natural structures, it is possible to develop metamaterials that exhibit low weight, high strength, and enhanced energy absorption properties. Furthermore, additive manufacturing technologies enable the fabrication of such metamaterials with unit cell geometries of arbitrary complexity. In this study, the microstructures of pomelo peels and the forewing of the Japanese rhinoceros beetle were used as source geometries for the design of metamaterials. Metamaterial specimens, consisting of 5 × 5 × 5-unit cells with an initial model porosity of 80%, were fabricated from Ti6Al4V alloy using the selective laser melting method. Quasi-static and dynamic compression tests were conducted to determine the mechanical properties and specific energy absorption of the metamaterials. The compressive yield strength of the metamaterial samples based on the Japanese rhinoceros beetle forewing microstructure was 134 MPa, compared to 115.87 MPa for those based on the pomelo peel microstructure. Under quasi-static compression, the energy absorption level of the metamaterial samples based on the rhinoceros beetle wing microstructure was 13.83 J, with a specific energy absorption of 4.61 J/g. The results demonstrate the overall promise of employing a bioinspired approach for designing energy-absorbing metamaterials. These findings will serve as a basis for further in-depth research and development of energy-absorbing systems and components based on the geometries presented in this work.