If you'd like to make melon balls, use a melon baller to scoop balls from a piece of cantaloupe/honeydew. If they are slightly flat on one side that's fine as it will then give a flatter edge for the ham to go next to. Alternatively, cut into cubes around the same width as the mozzarella balls.
Split the slices of prosciutto in half lengthwise and fold over back and forth concertina-style to make small stacks (you can also just break as it separates and stack neat-ish).
Use small skewers or slightly long cocktail sticks and thread each with a piece of melon, stack of prosciutto, basil leaf and ball of mozzarella. Repeat with additional skewers and ingredients.
Place the skewers on a serving plate and drizzle with a little balsamic glaze before serving.
Video
Notes
Scale up or down all the ingredients as needed for the quantity you plan to serve. It's hard to say how many you will need per person as they are all too easy to eat a few of! I use ciliegine size mozzarella balls for this which are small bite-sized pieces, around ⅓oz (10g) each.