Use your favorite devil's food cake recipe to make this classic American layer cake that gets dressed up with geraniums for an informal wedding.
Set each on a cardboard round at least 2 inches wider in diameter. Use an offset spatula to frost generously with frosting, creating a swoopy finish.
Place 1 dowel in center of largest tier, then 4 dowels in a circle 2 inches from center. In center of midsize tier, place remaining 4 dowels 1 1/2 inches apart in a square. These dowels will support the plastic drip trays.
In center of 14-inch plastic tray, glue 9-inch Styrofoam round. Cut floral foam blocks to measure 3 inches high, then cut 2 blocks into pieces to fit in the space between the Styrofoam round and the edge of 14-inch plastic tray. Cut remaining 2 blocks of foam into pieces to fill 6- and 4-inch trays.
At the reception site, place floral foam in sink filled with cool water. Once foam absorbs enough water to sink, return it to its drip tray. Place the prepared 14-inch drip tray on the cake table. Center prepared 6-inch drip tray on foam on the 16-inch tier and 4-inch drip tray on the 12-inch tier. Firmly attach 7-inch pillars to the 11- and 7-inch clear plastic separator plates. Center 11- inch separator plate, pillars pointing down, on the 16-inch tier, and push it straight down into tier until it can go no further. You may need to adjust drip tray slightly for pillars to fit around it. Place 7-inch separator plate on the 12-inch tier in the same way. Remove 16-inch tier from round and center on Styrofoam. Remove 12-inch tier from round and center on 11-inch separator plate; similarly place 8-inch tier on 7-inch plate.
Cut geranium stems long enough to reach floral foam so blossom extends just beyond tier above it. Use wooden skewer to create holes in foam for stems; gently push stems into foam.