Take a walk back to the '50's, when the whole world seemed to be Jello Land. Mom came home with this recipe:

7-Layer Jello Dessert
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1 sm box ea lime,orange,lemon & strawberry jello
2 c milk
1 c sugar
2 env unflavored gelatin
2 c sour cream
2 T vanilla

Dissolve lime jello in 1 c boiling water and add 1/2 c cold water. Pour into a 9x13" greased pan. Chill to set.
Boil milk, add sugar & mix til dissolved. Add gelatin dissolved in 1/2 c cold water. Add sour cream and vanilla. Beat til blended. Cool. Pour 1-1/2 c of this white mixture over set lime jello. Chill to set.
Prepare orange jello as you did the lime. Chill to set.
Continue with other flavors til done, putting some white mixture between each color layer.
NOTE: Keep unused while genatin over warm water til needed, so it won't set too soon.