For the caipirinha punch, grate the zest from 3 of the 12 limes, squeeze the juice from 5 limes.
Mix 300 ml of sparkling cold mineral water with the juice of the limes and the zest, pour into an ice cube mold and freeze.
Cut melon and remaining limes into pieces. Mix the lime pieces with sugar and crush with a mortar or pestle.
Add melon pieces and brandy and refrigerate for at least 3 hours.
Just before serving, add the remaining mineral water, sparkling wine, and ice cubes. Serve the caipirinha punch in glasses with a sugar rim and a slice of lime.