Method for manufacturing an object and packaging

A method for manufacturing an object having at least a wall and a flange arranged to an edge of said wall and under an angle larger than 45° to said wall, the method comprising:

• providing an unfolded sheet;
• providing a straight score line in the unfolded sheet for providing a division between a wall part and a flange part and for folding the flange part relative to the wall part, wherein the unfolded sheet includes at least one U-shaped cut arranged in the sheet interrupting the score line, wherein free ends of the U-shaped cut are positioned on the score line and wherein a bridging part of the U-shaped cut is positioned in the flange part;
• folding the flange part of the unfolded sheet relative to the wall part along the score line to provide an angle larger than 45° between the flange part and the wall part thereby defining a recess due to the U-shaped cut as well as a lip, which is positioned in front of the recess;
• providing a plastic foil;
• heating the plastic foil;
• and
• pressing the heated foil on the sheet at a side provided with the score line and covering at least part of the wall part, the flange part and at least one U-shaped cut, such that when the heated plastic foil cools the foil will shrink and pull the lip of the wall part into the recess to accommodate the lip in the recess to provide a locking of the flexibility of the flange part relative to the wall part over the score line such that the wall part in the region of the U-shaped cut is deformed to provide additional structural stiffness.