Cut the melon. Slice cantaloupe and watermelon into ½-inch thick rounds Cut from the side of the cantaloupe to avoid the seed pocket. Use the flower-shaped cutter to punch out flower shapes from both fruits.
Make the centers. Use a small round cutter to create circular melon pieces from the center of the flowers.
Slice the grapes. Cut grapes in half lengthwise. These become the "leaves" at the base of each kabob.
Add the grapes to the skewers. Thread 2 grape halves beneath the flower, angled with the cut side slightly facing inward to mimic leaves. You'll want to insert the skewer above the grape seed where it is firmer, so that it doesn't move around on the stick.
Assemble the flowers. Place a round melon center into a contrasting-colored flower.
Place a melon center into a flower shape of a different color.
Insert the skewer from the bottom of the flower, aiming for the rounded edge of a petal (not between petals). Push through the fruit until the stick passes through the center and just begins to reach the petals again. Stop before it pokes through the top—your stick should look like a stem.
Serve or store. Arrange on a platter or stand upright in cups to look like bouquets. Keep chilled until ready to serve.