Assemble tiers: Trim tops of 12-inch cake layers level. Cut each in half horizontally, making 4 layers total. Set 1 layer on same-size foam board. Pipe a thick line of buttercream around outside of layer to serve as a dam, then fill with lemon curd (see buttercream and curd amounts for each tier, above). Repeat with remaining 12-inch layers, spreading lemon curd on second and third layers, stacking them, and finishing with cake. Spread a thin layer of buttercream over top and sides of finished tier, and refrigerate until buttercream is firm, 30 minutes to 1 hour. Repeat with 6- and 10-inch tiers (do not cut in half), placing the bottom layer of each on corresponding-size foam board.
Once each tier's crumb coat has set, remove tier from refrigerator, and spread a thick, smooth layer of buttercream over tier. Chill to set frosting.
Stack cake: Insert 1 dowel in highest spot of 12-inch tier, and mark where top of tier falls. Remove dowel, and use dowel cutters to cut at mark. Trim 11 dowels to match. Insert the 12 trimmed dowels into the tier, placing 8 in a circle about 2 inches from edge, and 4 in a square at the center. Repeat for 10-inch tier, placing 4 in the center so they will support the small cake stand. Place bottom tier on the large cake stand; top with middle tier. Then, carefully set small cake stand on middle tier, aligning it with dowels and pressing gently until it is securely supported; place top tier on cake stand.
Decorate cake: Fill a pastry bag with two colors of buttercream at once, placing yellow on the left side and white on the right. Fit with a ribbon tip (such as Ateco No. 45, for bottom tier, and No. 44, for others); pipe bands 17/8 or 11/4 inch apart. Change to a petal tip (Ateco No. 101); pipe flowers in centers where bands meet.
Adorn your wedding cake with one of these thoughtful handmade touches.See the Ideas