Prepare 3 in. high cake for rolled fondant. Tint 72 oz. fondant light blue.
Cover cake; smooth with Fondant Smoother. For cake sides, roll out remaining blue fondant 1/8 in. thick. Imprint star design following instructions on Imprint Mat package. Cut strips to fit cake sides; attach with damp brush. Add a small amount of White-White to piping gel. Using tip 1, outline stars, then use decorating brush to fill in area. Using full-strength White-White and fine tip brush, fill in swirls; repeat 2-3 times if needed. Using buttercream, pipe tip 3 beads on side seams.