Preheat oven to 350 degrees F. Spray a 9x13 baking pan with no stick cooking spray.
Place the cake mix into a large mixing bowl, add the water, oil and eggs. Beat with an electric mixer, on medium speed, for 2 minutes. Spread the batter evenly into the pan.
Bake about 25-27 minutes or until cake is light golden brown and toothpick inserted in the center comes out clean. Remove from the oven and allow to cool completely.
Prepare the instant pudding according to directions on the box. Chill in refrigerator.
After the cake is cool, using a 2 1/2-3-inch round cutter, cut circles out of the cake. Place on a serving tray and cover with Cling Wrap until ready to set on the cupcake bar.
Place all of the filling, pudding, candies, nuts and toppings in serving dishes.
Arrange all of your ingredients in order of building the cupcakes.