A method for applying a heat-shrink patch to a carton for forming a shape of the carton. The carton includes a top panel, a bottom panel, at least one side panel extending between the top panel and the bottom panel and a movable section that is movable between a first position and a second position. The method includes providing a heat-shrink patch in a pre-shrunk configuration. The heat-shrink patch is coupled in the pre-shrunk configuration to at least a portion of an interior surface of a blank of sheet material including at least a portion of the movable section. The carton is formed from the blank of sheet material. The movable section is moved from the first position to the second position to form the shape of the carton by heating the heat-shrink patch to shrink the heat-shrink patch to a shrunk configuration.