Measure out the ginger beer and set it aside for 15-30 minutes while you prepare other ingredients. This will help some of the carbonation dissipate, but not go flat.
Mist 12 cups or molds lightly with cooking spray. (Skip this step if using lime shells.)
In a small saucepan over medium heat, combine sugar and ginger beer. Stir until sugar dissolves. Do not boil. Remove from heat.
Add the lime juice to a medium bowl. Sprinkle gelatin over top and allow to rest for 5 minutes until gelatin is softened and the liquid’s surface appears slightly wrinkled.
Stir the lime-gelatin mixture into the ginger beer mixture. Warm over medium heat for 2 to 3 minutes, stirring until gelatin is completely dissolved. Do not let boil. Remove from heat. Stir in the vodka.
Then, pour into the molds. Distribute evenly among the molds.
Refrigerate 3 to 4 hours before serving. If using lime shells, cut in half to create lime wedges before serving.