B65D 5/103

Rigid or semi-rigid containers of polygonal cross-section, e.g. boxes, cartons or trays, formed by folding or erecting one or more blanks made of paper by folding or erecting a single blank to form a tubular body with or without subsequent folding operations, or the addition of separate elements, to close the ends of the body with end closures formed by inward-folding of self-locking flaps hinged to tubular body {one of the self-locking flaps having a tongue engaging into an opening of an opposite flap}