Different color themes would be really fun depending on what you're making this for. What little princess wouldn't love purple & pink "jeweled jello" at a party? Or, how about Superbowl team colors? :) Go Steelers!
4 small boxes of jello, different colors
1 can sweetened condensed milk
2 envelopes unflavored gelatin
Dissolve each box of jello separately, into one cup of hot water. Pour into individual containers (small tupperware works well) and chill overnight.
Ready a 9×13 pan.
Cut flavors of jello into small blocks.
Mix together carefully in pan.
In a separate bowl, dissolve 2 envelopes unflavored gelatin in 1/4 cup cold water. Add dissolved gelatin to 1 3/4 cup hot water and condensed milk. Cool.
Pour cooled milk mixture over jello and chill overnight.