a dense fill material is loaded onto the bottom panel prior to closure providing mass for strength and stability against impacts the flat panels may be hingeably interconnected and foldable to optionally form a compact stackable configuration for storage and transport a multiplicity of such modules may be positioned and connected to form a continuous massive wall for such uses as reducing damaging wave action preventing beach erosion directing water in flood areas and providing highway barriers for guidance and safety application_number US 93281901 A description 0037 fig1 illustrates a preferred embodiment of the present invention under construction having modules in the complete partially complete and unfolded conditions panels 1 2 and 3 have identical rectangular dimensions in his embodiment and are firmly and hingeably communicated at edges 4 and 5 in a manner such that panels rotate freely with respect to each other panels are preferably made of a durable lightweight material such as plastic composite or wood triangular panels 6 and 7 are firmly and hingeably communicated at edges 8 and 9 to panel 1 completed module 10 forms a prismatic hollow structure which is weighted down by fill material 11 also shown being manually loaded into partially completed module 12 prismatic is herein defined as a polyhedron having parallel congruent polygons as bases.