Cut the melons into neat halves and scoop out the flesh using a fruit baller. Scoop out as many neat balls as possible and then scrape off the rest of the melon flesh with a knife. Set aside the empty shells.
Halve the papaya without peeling and similarly scoop out the fruit into as many neat balls as possible.
Peel the whole mango without cutting and again scoop out the flesh into balls
Toss together the fruits, cover and refrigerate until serving time.