Abstract: A continuous blank for forming a folded object is made from a multi-layered board material including a corrugated layer defining a flute direction (F); the blank including two blank portions joined to each other by a straight fold line extending along the flute direction (F) and having two opposed fold line end points, the multi-layered board material being weakened along the fold line. A contour of the blank includes two recessed contour portions, each recessed contour portion including one of the end points and extending on both sides of the fold line.

Abstract: A packaging box is disclosed, able to have smoothly curved wall portions. The box includes a perimeter wall defining a void thereby. The perimeter wall includes a first fold line and a second fold line. The first fold line and the second fold line may be parallel. A distance around the perimeter wall from the first fold line to the second fold line measured in a first plane perpendicular to the first and second fold lines in a first rotational sense is the same as a distance around the perimeter wall from the first fold line to the second fold line in the first plane in a second rotational sense opposite to the first rotational sense. When the first fold line is fully unfolded, the perimeter has a continuous surface including the first fold line. A tube, blank, method and machine for forming the box are also disclosed.