Cut foam board into rounds, one each of the following diameters: 18, 16, 14, 12, 10, 8, and 6 inches. Make Swiss meringue buttercream. Place the tiers on the corresponding-size foam-board rounds, and fill and frost each cake tier with the buttercream.
Insert 9 dowels into the 18-inch tier: Place 1 in the center, and then place the remaining 8 dowels, evenly spaced, about 7 inches out from the center dowel. Insert 7 dowels into the 16-inch tier in the same fashion, placing 1 in the center and the remaining 6 surrounding it 6 inches from the center. Repeat with the 14-, 12-, and 10-inch tiers, inserting 5 dowels (1 in the center, 4 surrounding) in each, placing them 5, 4, and 3 inches from the center, respectively. Insert 4 dowels into the 8-inch tier; this tier should not need a center dowel, and the dowels should be placed 2 1/2 inches from the center point.
At assembly time, center the 18-inch tier on the 20-inch wooden base or platter. Carefully stack the tiers on one another, centering them. Place buttercream in a pastry bag fitted with a 1/4-inch plain (#10) round tip. Pipe a simple pearl border around the base of each tier. Store in the refrigerator until ready to display. Just before displaying, use a small dot of the remaining buttercream in the pastry bag to attach the meringue daisies to the cake.
Adorn your wedding cake with one of these thoughtful handmade touches.See the Ideas