1. In a blender, combine pineapple and 2 tablespoons sugar and blend until smooth, scraping down sides as necessary. Pour through a fine-mesh sieve into a medium bowl, pressing on solids (you should have about 1 1/2 cups puree); discard solids. Rinse out blender. Add strawberries, 1/4 cup juice, and 2 tablespoons sugar; blend until smooth. Pour through a clean sieve into another medium bowl, pressing on solids (you should have about 1 1/2 cups puree); discard solids. Repeat process with mango, 1/4 cup juice, and 2 tablespoons sugar (you should have about 1 1/2 cups puree).

2. Divide pineapple puree evenly among six 8-ounce plastic cups. Freeze just until frozen, 45 minutes. Pour a layer of strawberry puree over pineapple layer, dividing evenly. Top with mango puree and insert ice-pop sticks. Freeze until solid, 6 hours (or up to 2 weeks).