A scaled model is proposed for the low lying vibrational modes of a sintered metallic powder. Such states provide a possible contribution to the metal/liquid He Kapitza conductance anomaly found experimentally below 20 mK. The density of states and degree of localisation of the modes are calculated. The results support the 'shaking box' viewpoint that the active states in the 10-20 mK region are formed from the collective motion of small localised groups of powder particles.