In a small saucepan over medium-low heat combine watermelon juice, lemon juice, and honey. Whisk until well combined. Slowly whisk in gelatin and whisk until completely dissolved and slightly thickened. This should take a few minutes. Alternatively, if your gelatin isn't dissolving as you'd like, place in blender and whirl away.
Pour into candy molds or in a shallow baking dish. Refrigerate until firm, about 45 minutes.
For a vegetarian version, you can try using agar-agar powder but note agar-agar does not have the same gut healing benefits. The ratio is 1 tsp. agar-agar to 1 cup liquid, but I have not tested this so if you do let me know how it turns out!