Several days before decorating cake make palm trees. Cover backs of each mini ball cavity with an aluminum foil square; spray with vegetable pan spray. Using tip 366 and royal icing, pipe 6 leaves starting at the top center of the mini ball and pulling icing out to sides of the mini ball forming the top of the palm tree. Let dry overnight. Carefully remove foil from tree top; turn over tree top and pipe tip 12 royal icing mound in center. Trim ½ in. from end of pretzel rod; insert into icing. Let dry completely.
Bake your favorite 2-layer cake recipe or mix in round pan. Cool cake in pan on wire rack 10 minutes. Remove from pan and cool completely. Arrange cake on foil-wrapped cake board.
Tint small portion of icing dark green; tint remaining icing light green. Ice cake smooth with light green icing; add blue gel on cake top for water "lake". Pipe tip 16 dark green pull-out grass tufts; insert palm trees. Sprinkle granulated brown sugar "sand" around tufts of grass. Attach icing decorations to cake sides. Add tip 16 pull-out grass bottom border; position toppers.