Make cookies. Prepare and roll out dough following recipe directions. Use straight side of square cut-out "A" to cut cookies. Bake and cool cookies.
Decorate cookies. Prepare buttercream icing following recipe directions. Tint portions light blue, medium blue and dark blue.
Use tip 2B smooth side up, cut disposable decorating bag, and medium blue icing, to pipe stripes on cookie. Use spatula to smooth. (Using tip 2B will give the icing a nice straight edge; if you don't have tip 2B, a spatula can also be used to cover the cookie.)
Use tip 47 smooth side up, and dark blue icing, tip 46 smooth side up and light blue icing, and cut disposable decorating bags to pipe flowing stripes on cookie. Use spatula to make waves.
Make fins. Tint 2 oz. of fondant gray (use a little black icing color to make gray). Use fondant roller with purple guide rings to roll out fondant 1/8 in. thick. Use pattern and knife to cut fins. Position fin on cookie.