Research on structural materials have shown advantages including lightweight, damage-tolerant, and high energy-absorbing properties. Previous research shows an efficient method of energy trapping harnessing nonlinear instability of 3D printed beam geometries. Here, we design and 3D print energy absorbing structures with tunable densities of 0.07-0.2 g/cm^3 and specific energies of 0.19-1.42 J/(kg/mm^3). The structures are elastic stackable hollow truncated cones, and their mechanical behaviors are characterized by numerical simulations and a series of compression and cyclic loading experiments. These designs have potential applications in personal protection and impact mitigation.