1. Spray 9x13 pan with cooking spray and set aside.
2. The key is to make one layer at a time.
3. Start with the 3 oz. box of red gelatin.  Boil 1 cup water in a 2-cup glass measuring cup in the microwave. Add the cherry or raspberry Jello powder. Stir until all the gelatin is dissolved. Then, divide that liquid in half into 2 bowls. (I like to just pour half into a 1-cup glass measuring cup and keep the other half in the cup you boiled water in.) 
4. To one half, add 2 Tbsp. cold water.
5. To the other half, add 1/3 cup sour cream and mix until incorporated.
6. Pour the cherry gelatin with cold water into the pan.
7. Refrigerate for at least 20 minutes.
8. Then pour the red jello with sour cream onto the first red layer.
9. *Then, you will just repeat for all the layers. You can do them in any order, but I prefer red, orange, yellow, green, blue, violet.

To recap: 1st layer: red jello with water; refrigerate 20 minutes; 2nd layer: red jello with sour cream; refrigerate 20 minutes; 3rd layer: orange jello with water; refrigerate 20 minutes; 4th layer: orange jello with sour cream; refrigerate 20 minutes.

1. Repeat for all layers. Right before serving, top with cool whip or whipped cream.
2. *Make sure the jello you are adding is cool so that it won't melt the previous layer. To speed up the process, you can make two flavors at a time and let the other one cool while the first one is setting up.