18 skewers (if wooden, soak in water for 20 minutes)
Remove the rind of the watermelon, the skin and eyes of the pineapple, and the peels and pits of the mangoes and discard. Split the pineapple in half and cut out and discard the hard core. Cut the fruit into 1-inch cubes and thread onto the skewers. Add half the lime zest and all of the lime juice to a small bowl and mix. Pour evenly over the assembled skewers. Store in the refrigerator at least 30 minutes, or until ready to use.
Combine the remaining lime zest with the chile powder and sea salt in a small bowl. Sprinkle over the fruit. Serve with fresh lime wedges and additional sea salt, if desired.
Baby version: Combine 1-inch cubed watermelon, pineapple and mango in a small cup. Serve with spoon or fork, if desired.