Wash all fresh fruit thoroughly. Peel the mango and cantaloupe, then cut them into bite-sized pieces. Peel the mandarin oranges and remove as much of the white pith as possible. Slice the bananas last to keep them fresh.
To keep the bananas and apples (if using) from turning brown while sitting on the board, lightly toss the white fruit segments in a small bowl with a tablespoon of lemon juice.
On a large rectangular or oval serving platter, create a wide horizontal band at the bottom using your yellow fruits. Mix the pineapple and mango together to provide different textures within the yellow layer. This should be the widest part of your triangle shape.
Place the mandarin oranges and cantaloupe chunks in a layer directly above the yellow fruit. Taper the sides slightly inward as you move up to begin forming the triangle shape characteristic of candy corn.
Finish the board by placing the sliced bananas and mini marshmallows at the very top. Arrange them into a rounded point to complete the candy corn silhouette. Ensure the white section is the smallest of the three layers.