After processing the watermelon, strawberries, lime juice, and ice, taste before adding sugar; you may not need any. For the star garnish, an adult can press a cookie cutter through the rind with the back of a wooden spoon.
Not every gelatin is meant to be completely firm. Halfway between a drink and a dessert, these loose-set watermelon treats include chunks of the fruit. If you like, top them with cubes of rose hip-hibiscus gelee flavored with fresh mint and basil. The bracing results combine seasonality and different textures sure to tempt any palate.
For a dessert you can serve in "fruitful" bowls, fill hollowed-out watermelon halves with slices of papaya, honeydew, and cantaloupe, as well as balls of the watermelon -- all sprinkled with lime zest.