Try this Knox Blox recipe, or contribute your own.
Each envelope of unflavored gelatin will set 2 cups of liquid. In bowl sprinkle gelatin over cold juice; let stand 1 minute. Add hot juice and stir until gelatin is completly dissolved. Pour into 13X9 baking pan. Chill until firm. Cut into 1" squares. Makes about 9 dozen.
Variation: With flavored Jello, omit fruit juice. In bowl, mix unflavored gelatin with 3 packages (4 serving size) fruit flavored Jello. Add 4C boiling water and stir until Jello is completely dissolved. Chill and cut as above.