Decorate front house panel design in advance. Place front house panel on parchment paper-covered surface. Position diamond stencil from kit on panel, leaving 2 1/4 in. open at bottom. Use spatula and white icing from kit to ice stencil openings. Carefully lift off stencil. Use round tip, cut decorating bag and white icing to pipe a line, 3/8 in. wide, below diamond pattern. Let dry, about 3 hours.