Mix royal icing to fluffy consistency. Place waxed paper over pattern and secure with minimum amount of tape. Outline design with desired color, piping with a number 2 tip. Add a small amount of water to icing until just barely fluid, not watery. Test consistency by testing a small amount on waxed paper. It should smooth itself in about 10 seconds. Color thinned icing and put in pastry bag with tiny opening. Fill in the outline with the thinned icing. Let each color dry before adding an adjacent colors. Allow at least 24 hours to dry. With pattern as guide and using a fine brush and food coloring, paint in details. Allow details to dry. Pulling gently on waxed paper, move finished piece to edge of working surface. Hold one hand under the piece, and with the other hand, pull waxed paper from the bottom, working it loose from one side to the other. Attach piece to cake. To avoid grease soaking through the run sugar piece, use royal icing underneath the run sugar piece.