a mask is assembled from a single blank . the blank is creased and folded to make a front , top and a back panel , with the top panel folding down to make two side panels . the side panels cooperate with the front and back panels by connections protruding from the panels . the mask can be stored or shipped in a flat two - dimensional , unassembled mode and can be opened or assembled to a three - dimensional form , which may be worn on the head of a user .