Abstract: A container is assembled from several panels generally comprised of one or more layers of relatively rigid stiffening material (such as corrugated cardboard) sandwiched between two layers of a strong, flexible material, such as woven polypropylene. These panels form four side wall assemblies and, in combination with a flexible bottom panel, form a self-supporting, generally cubic material receiving box. An integral closure assembly, including cover flap, front flap and side flaps, advantageously enable the container to conveniently and safely secure relatively large volumes of dense debris without spillage even when the fully laden container is dropped during handling. The container, when empty, may be collapsed for convenient storage.