1.Preheat oven to 180°C/350°F. Grease cake pan; line base with baking paper.
2.Make cakes according to directions on packets; pour mixture into pan. Bake about 45 minutes. Stand in pan 5 minutes before turning top-side up onto a wire rack to cool.
3.Using a serrated knife, level cake top; place cake, cut-side down, on cake board, securing with a little butter cream.
4.Tint one-third of the butter cream pale blue; tint remaining butter cream a darker blue. Using the picture as a guide, spread pale blue butter cream over both ends of the cake. Reserve 1 tablespoon of the darker blue butter cream; spread remainder over the rest of the cake.
5.Place sugar and blue colouring in a small plastic bag; rub until sugar is evenly coloured. Sprinkle over pale blue butter cream.
6.Cut two Roll-Ups into four fin-shaped pieces. Form two fins by joining pieces together with a little water, trim if needed. Place fins at the start of the dark blue section on each end. Cut two 5cm x 9cm (2-inch x 3¾-inch) triangles from Roll-Ups; join together with a little water, place on cake at centre of the figure for a tail. Cut four 1cm x 6cm (½-inch x 2½-inch) strips from remaining Roll-Ups, shape one end into a curve; join two pieces with a little water. Place on cake as mouths.
7.Position Smarties on dark blue butter cream for scales. Cut licorice strap into thin strips; position on cake to outline fins, tails and mouths. Place Mentos on heads for eyes, pipe with red decorating gel.
8.Cut wafers in half on the diagonal; position two pieces for heads and eight pieces for spines. Spread reserved butter cream on wafers; cover with orange sprinkles.
If you are unable to buy apricot Roll-Ups use your favourite flavour.Note