Stick the parts together with sugar syrup or tiny dabs of buttercream, and then add finishing touches with other fondant colors and sculpting tools.
Baking a cake in a 3D pan is a great way to create a stunning figure for any occasion without all the extra work of sculpting the cake by hand.
Alternatively, use fondant to create a rainbow that goes up and over a tiered cake, with a leprechaun made of sculpting fondant or modeling chocolate sitting on one of the middle tiers below.
Advanced decorators can show off some skills by sculpting a cake into a cloud or even a pillow with the graduate's head sticking out from the covers.
Eden Home also sells organic sculpting dough and is a member of the Organic Trade Association.