Halve the lemons lengthwise and gently scrape out the pulp and white pith with a spoon or melon baller. Put the rinds in muffin tins or fit them into a pan so they can be filled without tipping over.
Put 3/4 cup cold water in a small saucepan, sprinkle the gelatin evenly over the top and let it absorb the water for 2 minutes. Bring the water just to a boil and whisk until the gelatin is fully dissolved. Remove from the heat and whisk in the sugar until dissolved.
Transfer the gelatin mixture to a bowl and stir in the pink lemonade, cherry soda and vodka. Spoon the mixture into the lemon rinds. Refrigerate overnight.
Carefully slice each lemon half into 2 wedges and serve.