Tart citrus balances the mellow sweetness of watermelon and cantaloupe, each frozen in layers. You can use any mold you like for these popsicles, but you'll get a different number of pops depending on the mold size.
1/2 teaspoon very finely grated lime zest (use a box grater)
1/4 cup lime juice
7 to 8 tbsp. light agave nectar, divided
1 1/2 cups cubed ripe cantaloupe
2 1/2 cups cubed seedless watermelon
How to Make It
In a glass measuring cup, combine lime zest and juice, 2 tbsp. agave, and 6 tbsp. water. Taste and add more agave if you like. Divide mixture among 8 (1/3 cup) popsicle molds*. Cover and freeze until partially solid, 1 to 1 1/2 hours.
Meanwhile, in a food processor, whirl cantaloupe and 2 tbsp. agave until smooth. Transfer to a glass measuring cup and chill in refrigerator. Rinse food processor bowl, then whirl watermelon and 3 tbsp. agave until smooth. Pour mixture into another glass measuring cup and chill.
Stir cantaloupe purée and divide among popsicle molds. Freeze until partially solid, 1 hour. Stir watermelon mixture, then spoon an equal amount into each popsicle mold. Press popsicle sticks through all the layers. Cover and freeze pops until solid, 2 to 3 hours more.
To remove popsicles from molds, either let sit at room temperature 5 minutes or run molds under warm water 10 to 15 seconds. (If molds are metal, cut the time to just a second; otherwise the pops melt.)