The box is assembled from a single part that comprises a base surface (2) attached to folding side sections used to increase the size of the opening in the top of the box. The side is assembled from a single part that comprises a base surface (2) attached to folding side sections used to increase the size of the opening in the top of the box. The side sections are double-walled sidewalls (3-10) folded along their width at their central points. The sidewalls are separated by joining flaps (21-28) that extend for half the length of the sidewalls and can be inserted from one or both sides into a slot (11-18) in an adjacent sidewall.
