A collapsible, open cell void filler (2) is made by stacking a series of paper core sheets (58) and gluing the core sheets to one another at appropriate points (56) to create a generally hexagonal open cell core structure when expanded. The stack (60) of core sheets is cut along a series of cutting planes...http://www.google.es/patents/US4865889?utm_source=gb-gplus-sharePatente US4865889 - Void filler and method for manufacture
