A method of forming a cushioning element. The method including placing a first sheet adjacent to an outer surface of a first mold portion, the first mold portion including a first mold cavity. The method including pressing a portion of the first sheet into the first mold portion and into the first mold cavity with a forming tool, wherein at least a portion of the forming tool is extended into the first mold cavity. The method including applying negative pressure to the first mold cavity to draw the portion of the first sheet into the first mold cavity, and joining a second sheet to the first sheet to form the cushioning element.