Several days in advance: Make bow loops. Add 2 teaspoons of Gum-Tex to each 24 oz. of fondant (192 oz. will be needed). Roll out 1/8 in. thick. For 16 in. cake, make approximately 40 loops, cutting a 1 3/8 in. wide x 16-18 in. long strip for each. For 12 in. cake, make approximately 30 loops, cutting a 1 3/8 x 12-14 in. long strip for each. For top bow, make approximately 18 loops, cutting a 1 in. wide x 11-12 in. long strip for each. Brush one end of strips with water, fold over and secure ends to form loops. Let dry on sides for several days on cornstarch-dusted board. When dry, brush loops with Pearl Dust. On 6 in. plate, assemble top bow using royal icing; let dry. Also: Prepare grape clusters. Mix Meringue Powder with a little water; brush onto grapes, then sprinkle with sugar.