We used three-ounce baba-au-rhum molds to make these fruit-filled gelatin desserts; small ramekins or nonstick muffin tins work just as well.
In a small bowl, sprinkle gelatin over 1 cup water. Let stand 5 minutes to soften. Bring remaining 2 cups water and sugar to a boil in a small saucepan over medium-high heat, stirring to dissolve. Stir gelatin mixture into pan; cook until dissolved, about 30 seconds. Set aside to cool, and stir in sambuca.
Cut the papaya into 1/2-inch dice. Cut mango into 1/4-inch-thick slices. Cut the strawberries into thin wedges. Use two different-size melon ballers to scoop out cantaloupe and watermelon.
On a rimmed baking sheet, line up 24 molds (3 ounces). Place a few pieces of assorted fruit (including whole raspberries) in each mold, and pour 1 to 2 teaspoons gelatin mixture over the fruit. Refrigerate 15 minutes.
Fill molds three-quarters full with remaining fruit. Add enough gelatin mixture to cover fruit, leaving 1/4 inch at the top. Refrigerate another 15 minutes. Fill with remaining gelatin mixture, covering any fruit that has floated to the top. Cover with plastic wrap, and refrigerate until completely set, at least overnight.
When ready to serve, place molds in hot water for 5 seconds. Tap sides against countertop; invert onto a serving tray.