Prepare the red gelatin by mixing it with 1 cup boiling water until dissolved, then stir in 1/2 cup cold water.
Pour a layer into each cup and refrigerate for 30–45 minutes until set.
In a small bowl, dissolve unflavored gelatin in 1/2 cup hot water. Let it cool slightly, then mix with whipped topping to create the white layer.
Spoon or gently pour the white mixture over the set red layer. Chill again until firm.
Prepare the blue gelatin the same way as the red. Let it cool slightly before adding.
Carefully pour the blue layer on top of the white layer.
Refrigerate for at least 2–3 hours or until fully set.
Serve chilled and enjoy.