Combine fruit juice or kombucha and honey/maple syrup if using in a small saucepan.
Heat over low heat until warm and starting to simmer, but not hot or boiling.
Add pureed fruit, if using.
Sprinkle the gelatin over the juice mixture while whisking or using an immersion blender. Continue doing this until all gelatin is incorporated and the mixture is smooth. Adding the gelatin too quickly will make it more difficult to get the mixture to incorporate. An immersion blender is not necessary but greatly speeds up the process.
As soon as the gelatin is mixed in and the mixture is smooth, pour into molds or a lined/greased baking dish and place in the refrigerator or freezer until hardened.
It is important to have all ingredients ready before beginning as you'll need to work quickly once you start.
Make sure you are using gelatin, not collagen hydrolysate or peptides as they will not gel. I've also had some feedback that the Great Lakes brand of gelatin doesn't work well in this recipe.