I am fascinated by spheres. I find the shape of a sphere ball cake not only puzzling, but eye-pleasing.
A modified sphere shape used in a jack o’lantern cake:
As a very angry, irate, bird:
In a global cake:
Another example in a modern chocolate cake:
Tips & Tricks
The issue arises when a sphere is carved out of all cake, the bottom of the cake sinks and compresses due to lack of support from the inward curve:
This results in gravity compressing the bottom few inches of the cake over time. The bottom of the cake or fondant may bulge and/or ripple.
The secret is to construct the bottom 1/2 to 1/4 out of material other than cake. This can include a number of materials. Most commonly used are rice cereal treats, modelling chocolate, or polystyrene foam.
A similar concept is used here in the building of a cylinder shaped cake, used here as a camera lens in a cake. Here the side of a fondant bucket was used in the bottom 1/4, to allow for maximum cake content:
It is also possible to create the look of a sphere using all cake. This can be done creating only the top 3/4 of a sphere, and having a flat base. Another option is to use a heavy dense cake.
For carving itself, I prefer to carve from sheets or rounds of cake, as they bake evenly, however ball cake pans do exist.
Here is an excellent tutorial on carving a sphere out of ice. The same concept applies for cake – start with cylinder shape as tall as it is wide, then round the shape from all angles. Another tip I have learned is to use a half circle (negative) template as a guide.
The greatest challenge is covering a sphere cake in fondant. To give plenty of fondant to work with, if my sphere is 8 inches tall, I roll out my fondant in a circle to at least 16 inches wide. About 1/3 of this fondant will be cut away at the bottom.
Considerable excess fondant will gather around the base. From my own struggles, I have learned to pinch and cut away excess fondant using scissors, then blend in seams.
Another option is to divide the job in two, by splitting into a front and back section, then blending the seams.
For more details about cake sculpting, the book “Cake Sculpture and Sculptered Figure Piping” by the amazing Roland Winbeckler helped me. This book contains practical directions on building internal cake structures, plus lots of detailed information on sculpting with buttercream. Also, the phenomenal Mike McCarey has specialized class events on cake sculpting.
And if you share my fascination with spheres, you might also enjoy the art of the dorodango mud ball. I made one once. It was neat.