I'm going to be baking a 11 x 15 sheet cake and want to know what size cake board do I use and what size box do I need to buy. I have looked on line but there doesn't seem to be a size that that fits that size cake. Any and all help would be greatly appreciated. Also what is the best web site to purchase these things as there is no store in SW florida that have a good supply of cake decorating things.

This is not something that needs to be spot on to work. Just pick a cake board that is at least 2 inches bigger in dimensions than your cake and the matching box. For instance, Sugarshack has 13x18 that would work for your cake. Whatever size you get there should be a matching box the same size.
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