In three separate bowls, mix strawberry juice with 1–2 tbsp sweetener until dissolved.
In the second bowl, combine lime juice with sweetener to taste.
In the third bowl, stir blueberry juice and sweetener until well blended.
If juices are too concentrated, add water as needed to achieve balance.
Carefully pour or spoon the strawberry mixture into the bottom third of each popsicle mold.
Freeze for about 30–45 minutes, until firm to the touch but not fully frozen.
Layer the lime mixture on top of the strawberry layer and freeze again for 30–45 minutes.
Add the blueberry layer as the final layer and insert the popsicle sticks.
Freeze completely for at least 4–6 hours, or overnight, until solid.
To unmold, run the popsicle molds briefly under warm water and gently pull the sticks.