Line a baking tray with parchment. Dump the contents of the gelatin powder into three individual bowls.
Squeeze the contents of the lemon into a small bowl.
Take a grape and skewer with a toothpick. Dunk the grape into the lemon and then into the gelatin. Roll around until coated. Place the grape on the tray. Continue the process until all the grapes are coated.
Place the tray in the refrigerator until set, about 2 hours.