An appliance comprises a housing, a cover hinged to the housing, and a flap hinged to the housing walls, the flap and the cover having a central cut-out in their lower portion thereof. The flap and the cover having a plurality of opposite pairs of complementary shapes able to fit into each other after the cover is closed, a material strip able to be unwound between the flap and the inner wall of the cover. The complementary shapes are undulated shapes on the flap and the inner portion of the cover respectively, and form successive alternating convex and hollow shapes. One of the undulated shapes, transversely has a hollow cavity with a curvilinear profile near its end. The cavity is bordered by an undulated end shape having the same curvature as the undulations formed. The end shape is adjacent to the cavity forming in its inner side a stop zone.