I'm currently stacking a 6 inch round cake that will be approximately each inches high that I will be carving to look like a coffee cup. In order to support the cake, I'm thinking of putting a cake board and dowels after every 3 layers of cake. I'm just wonder should I put some buttercream on my 3rd layer of cake before I put dowel & put a cake board on. Will all the buttercream be stuck to the bottom of the cake board.
You want to add support every 4 inches of cake. And, yes, you do want BC between each layer...it will help cement the cake together and make it more stable.