Whisk together first 3 ingredients and 6 to 8 Tbsp. water until smooth. Divide mixture into 5 to 6 small bowls; tint icing in each bowl with desired food coloring paste or drops, stirring until blended.
Note: For testing purposes only, we used Wilton Meringue Powder. Meringue powder and food coloring paste can be found at crafts and cake-decorating stores.