Cut your watermelon into small cubes, removing any seeds. The smaller the cubes, the easier they'll blend. Choose a watermelon that sounds hollow when tapped for optimal sweetness.
Place watermelon chunks, lime juice, and optional honey in a blender. Pulse until smooth but not overly processed—about 30-45 seconds. Add the pinch of salt.
For ultra-smooth popsicles, strain the mixture through a fine-mesh sieve to remove pulp. This step is optional but creates a more commercial-like texture.
Pour the watermelon mixture into popsicle molds, leaving about 1/4 inch at the top as the liquid will expand when frozen.
Insert popsicle sticks and freeze for at least 4 hours, preferably overnight. If your molds don't have built-in sticks, freeze for 1.5 hours first, then insert sticks.
To remove popsicles, run warm water over the outside of the mold for about 15 seconds, then gently pull the popsicles out.