Place the white chocolate in a double boiler or heat in a glass bowl in the microwave at 30-second intervals. Mix with a spatula until completely melted.
Line a baking sheet with parchment paper.
In 4 separate cups, place 5-8 candy melts. Heat at 30 second intervals until heated. (Work quickly as you want all the chocolates to be melted and workable at the same time.) Pour 1/4 teaspoon of oil into each cup of colored chocolate to create a looser mixture if needed. Alternatively, you can melt more white chocolate in each cup and place 2-3 drops food coloring in each to create colored chocolate, but I prefer the chocolate melts as the color is more vibrant!
Working quickly, pour white chocolate onto the parchment-lined baking sheet, and spread evenly in a rectangle about 1/4-inch thick. Drizzle each color in random patterns over the rectangle, and, using a knife or skewer, swirl it through the surface of the chocolate to create a marble effect. Don't forget all the edges!
Place the baking sheet in the fridge to firm up. Once completely hardened, break apart into random shards. Store at room temperature or in the refrigerator.