Time-consuming, but well worth the effort.
1 small box lemon gelatin
1 small box strawberry gelatin
1 small box orange gelatin
1 small box lime gelatin
4 cups vanilla ice cream
1 pint sour cream
Prepare first box of gelatin according to directions, using 1 cup hot water and 1 cup ice cream. Stir until ice cream is melted. Pour into glass bowl or 13 x 9-inch glass dish. Chill until set. Spread a thin layer of sour cream over gelatin. Chill again - about 1/2 hour.
Repeat with second color of gelatin and again with sour cream, ending with a Jell-O layer.
Repeat with third and fourth colors of gelatin.