Cake Shape

• Choose a sheet cake if you need a larger cake -- to serve a large group -- or if you want to make an elaborate gymnastics-themed decoration. Sheet cakes are best-suited for novice or mid-level bakers who are not accustomed to making layer cakes or who are not as adept at icing complicated designs onto a cake. The broad expanse of a sheet cake means you have more room to maneuver. Round cakes make for stunning gymnastic cake designs when they are layered so that the design spreads from the top to the sides of the cake.

Edible Photo Prints

• The simplest way to make a gymnastics-themed birthday cake is to use an edible photo of either the celebrant or of an admired gymnast. Create edible photos by going to a bakery that can print out the image for you, or you can order online to have the photo printed on edible paper. Choose an action-based photo if possible, and select one that shows off a routine at which the birthday gymnast is especially adept. For example, you could make a photo collage of the person winning their noted event -- such as the vault -- as well as a shot of them doing the vault. Use a sheet cake for cakes with edible photos, as the rectangular shape and flat surface make them well-suited for this design option. Use white butter-cream icing as the base icing, as darker colors may make affect the appearance of the photo.

Floor Exercise Cake

• Design a floor exercise design onto a sheet cake using only icing. Because the design is primarily one dimensional, it's easier to execute and better suited for novice bakers. Start by drawing the outline onto a sheet of paper to ensure that proportions and shapes are accurate. Use exact measurements from your iced cake. Butter-cream icing or poured fondant work well as the base icing, as they harden sufficiently for you to easily ice on top of. You can also use cream cheese icing, but it is much softer, and the cake should be cooled prior to drawing on the floor exercise design. Use white for the base icing and draw a square for the floor mat in a contrasting color. Use butter-cream icing to design the floor mat as it takes well to coloring. Use a plastic figurine to mimic the gymnast, placing it on top of the floor mat in an active pose, such as the splits. For a more complicated design, apply fluted icing along the sides of the cake, to mimic a ribbon shape, such as those found on the sides of some grandstands. Leave enough space on the front of the cake to pipe the birthday message.

Bar and Beam Exercises

• Bar and beam exercises, such as the uneven bars and the balance beam, look more impressive on a round layer cake when they are 3D. Ice the cake in buttercream icing before covering in poured or rolled fondant. Use a white or pastel color for your base icing. To make the bars or beams, wrap rolled fondant around bamboo skewers or straws that have been cut to length, using fondant to hold the pieces together. Construct the gymnast figurine using different-colored pieces of fondant or marzipan. Decorate the sides of the cake with silver candy balls to mimic the sparkle of bright lights. Add rolled fondant cutouts, such as stars, to the cake, pasting them so that they extend past the edge. Use colored butter-cream icing to write the birthday message, either on the cake tray or, if there is room, on the surface or side of the cake.