It depend how large the sculpture is going to be, anything larger than a foot or two and i would say no for a recreational application.
A stronger medium to consider would be modeling Chocolate its easier to work with.
Instead of doing just cake as a base most cake decorators will use rice crispy treats, they are more light weight so gravity will not destroy your piece.
Also if you are really going to be working vertical you can use a copper tubing armature before applying the rice crispy's
