A collapsible and expandable void filler for separating cargo during transit in trucks, railroad cars, airplanes and the like includes an outer tubular housing having a diamond-shaped tubular core. The housing and core are collapsible into a generally flat configuration along score indentations. In one embodiment, the void filler is held in an expanded configuration by a plurality of collapsible wall portions along the outer housing that collapse inwardly from the periphery of the housing and engage the core. In other embodiments, the void filler is held in an expanded configuration by a cord or elastomeric bands which are tightly stretched around the periphery of the housing and is held in a series of aligned notches.