Physical principles for designing cellwise mechanical met-amaterials with energy-absorbing/harvesting and wave guiding properties are discussed in the present work. The evolution of both propagating and standing waves in a one-dimensional lattice of 3D massive potential wells with light particles inside is analyzed. The potential wells/containers represent soft-wall versions of chaotic billiards that coupled with elastic springs as a one-dimensional chain. The proposed shape function allows for a switch from the repelling to the stadium type of container walls by varying the shape control parameter. The results reveal how the geometry of containers affects the intensity and ir-reversibility of energy flows from the chain of containers into the ensemble of light inclusions. Typically, cells with repelling boundaries generate a chaotization of inclusions and hence the energy absorption in a faster temporal rate. As a result, propagating waves are trapped by giving rise to standing waves of chaotic mode shapes with decaying amplitudes.