Lay out containers on a baking sheet without the lids on. Set aside.
Pour the gelatin mix into a medium mixing bowl or 4-cup liquid measuring cup. Add the boiling water and whisk until gelatin is completely dissolved.
Stir the alcohol into the mixture, combining well.
Pour the mixture into the plastic cups, filling about 3/4 full.
Refrigerate for 2–3 hours or until set. Once set, place lids on each container and store in the fridge until ready to serve.