Stackable container blank, stackable container, and method for making the same

A container blank, a stackable container, and a method for making a stackable container are disclosed. The container blank includes a base having first and second pairs of opposed base edges, end walls foldably attached to the first base edges, and side walls foldably attached to the second base edges. Each side wall has an outer wall foldably attached to the second base edge along a first fold line, at least one index fold-down flap attached to the outer wall along a second fold line, and an inner wall or inner wall flaps foldably attached to the outer wall along a third fold line. Each index flap has a distal portion with notched or expanding extensions, and optionally, a border at a first angle of less than 90° from the second fold line. The stackable container is made from the container blank (e.g., by the method).