Sprinkle gelatin evenly over cold juice or water in a bowl.
Let it sit for 5 minutes until fully bloomed and spongy.
Add boiling water and stir thoroughly until completely dissolved.
Mix in sweetener or Kool-Aid if using.
Pour mixture into a dish or mold.
Refrigerate for 3–4 hours until fully set and firm.
Cut into cubes or serve as desired.
