Metamaterials, widely used in many engineering fields, are strategically designed materials that exhibit exceptional mechanical, chemical, and electromagnetic properties. In particular, soft lattice metamaterials, obtained by tessellation of unit cells (UCs) with truss- or beam-like microstructures made of hyperelastic or rubbery materials, undergo large elastic deformations. Their mechanical modeling necessitates the inclusion of nonlinear geometric effects [1]. This work focuses on the numerical analysis of large-deformation elastic responses of soft beam-lattice structures, employing nonlinear buckling analyses and three-dimensional beam finite elements. The considered UCs are assemblies of shear-deformable beams accounting for large displacements and finite strains. First, the linear buckling modes, are evaluated and, then, these are used to construct imperfect lattice structures with randomly distributed imperfections. In fact, the imperfections, tipically arising from manufacturing processes, impact on both load-displacement global curves and UC failure modes [2]. The study demonstrates that the considered initial imperfections significantly affect the numerical results. Therefore, the main objective is to thoroughly investigate these choices to strategically design the imperfections and drive the mechanical response. [1] L. E. Murr et al, Metal fabrication by additive manufacturing using laser and electron beam melting technologies, Journal of Materials Science & Technology (2012). [2] M. Jamshidian et al, Multiscale modelling of soft lattice metamaterials: Micromechanical nonlinear buckling analysis, experimental verification, and macroscale constitutive behaviour, International Journal of Mechanical Sciences 188 (2020).