For this watermelon-look-alike dessert, I combined the ideas of the Edible Layers of the Earth project and this recipe from Catholic Cuisine.
Pineapple sherbet (you could use vanilla ice cream instead)
Mini chocolate chips
Line the inside of the bowl with a layer of lime sherbet, about 1 inch thick. I am not giving amounts here because the size of bowls will vary.
Place bowl into the freezer for a few minutes until the sherbet hardens a bit. At the same time get the pineapple sherbet out of the freezer so that it can soften a bit while the green layer hardens.
Add a thin layer of pineapple sherbet about a 1/2 inch thick on top of the lime sherbet.
Return bowl to the freezer until hardened, and get out the raspberry sherbet.
Once the raspberry sherbet has softened, mix chocolate chips into a small bowl of it so that it looks like the seeds in a watermelon.
Fill the cavity that is left with the raspberry-chocolate chip sherbet. Press down firmly.