Tint piping gel blue and pipe in cut bag on cake top for water. Position candy.
Several days in advance, using 1 recipe candy clay, roll four marble-size balls for tub feet; let dry. Store leftover clay in cool, dry place. Add a small amount of melted white candy to yellow; mold ducks using painting method.
Cover rounded side of egg cakes with melted white candy; refrigerate to set. Attach feet to egg cakes with candy. Ice cake top smooth. Roll an 11 in. string of reserved candy clay and position around top edge of cake for rim of tub.
Adding color details to candies makes them more realistic and much more fun! For large areas of color, it's best to paint the melted candy right in the mold before the whole candy is molded using a decorator brush. Or, for very small details like vines, mouths and messages, melted candy should be piped onto molded candies using a parchment bag with a small hole cut in the tip.