Put one cup of the candy melt color you have selected for your bottom layer in a microwave-safe mixing bowl (batter bowl is ideal). Microwave on high for 1 minute. Stir, then repeat in 20-second intervals until the wafers are nearly melted. At that point, briskly mix until the remaining bits melt.
Add 2 cups of Rice Krispies® and mix well, until completely coated in the candy. Spread the mixture into the lined baking dish, and smooth with the back of a spoon. Place in refrigerator (to assist setting), while you wash and dry bowl and repeat the process for the next layer.
After final layer, melt a 1/2 cup of the candy wafers and drizzle on top, then repeat with another color. Immediately add the sprinkles so they will adhere.
DO NOT REFRIGERATE after this step. Allow the Rice Krispies® Bars to cool until set at room temperature. If too cold the bars will not cut well.