1 day in advance, make ears. Knead 1/8 teaspoon of Gum-Tex into 1 oz. blue fondant. Using 9 in. fondant roller, roll out fondant 1/8 in. thick. Using pattern and knife, cut out two shapes for ears, reversing pattern for second cut. Let dry on dusted lightly cornstarch-dusted cake board for 24 hours. Reserve remaining fondant.
Bake cake. Bake and cool one layer 2-in. high cake. Prepare buttercream icing according to recipe. Using spatula, ice cake lightly to prepare for fondant covering.
Cover cake. Roll out reserved blue fondant 1/8 in. thick and cover cake. Also using patterns and knife, cut out trunk and tail from blue fondant rolled 1/8 in. thick. Attach trunk to cake with damp brush. Reserve tail.
Add details to cake. Roll out black fondant, 1/16 in. thick. Using the smooth side of the E of double sided round cutter, cut out two eyes. Attach eyes using a damp brush. Roll out a 1/4 in. ball of white fondant to 1/16 in. thick. Using narrow end of tip 10, cut out two dots and attach to eyes with damp brush for highlights.
Make small amount fondant adhesive. Trim two lollipop sticks to 3 in. each. Attach one ear to each stick with adhesive. Let dry 1 to 2 hours.
Add ears. Insert lollipop sticks with attached ears into top sides of cake, approximately 3/8 in. down from top edge.
Add tail. Position tail to cake on plate or board with damp brush.