1. Cut a large round of watermelon to serve as the base, making sure the bottom and top of the round disc of watermelon is flat.
2. Layer toothpicks standing vertically on the watermelon, and place a disc of honeydew melon on top, repeating the toothpick process of top.
3. Next, place a thick circle of pineapple on top of the melon.
4. Now for the berry garnishes: make a circle of toothpicks sticking directly out of the "cake" between each layer of fruit. Add a circle of blueberries to the bottom layer, a circle of raspberries on the middle layer, and another circle of blueberries on top, each one held in place by a single toothpick.
5. Circle the base of the cake with loose berries on the plate for garnish, and fill any openings on the top of the pineapple section with any loose berries.