Tint 2 oz. fondant Royal Blue, 16 oz. each Black and Copper (skin tone), 8 oz. brown/red-red combination and 2 oz. each Lemon Yellow/Golden Yellow combination, Orange, Rose, Violet/Rose combination and Leaf Green.
For inner tubes, shape a 1 1/2 in. black ball into a log, then into a ring, attach ends with damp brush, smooth. Make 1 in. ball bodies and 3/4 in. ball heads using copper or brown. For arms and legs, shape 1/2 in. balls into logs; cut slits for fingers with craft knife. Attach kid pieces with damp brush, positioning bodies in various ways. For bathing suits, roll out fondant 1/16 in. thick; cut strips and shape around body, attaching with damp brush. Let dry several hours.
Roll and attach a small ball for nose; draw facial features with FoodWriter marker. Pipe tip 2 hair using royal icing; let dry. Attach kids to inner tubes with damp brush.