Clean all citrus fruit and cut off waxy outer skin. Blend in a food processor using an S-blade. Spoon into ice trays and freeze. 
 
Approximate yields (depending on how juicy your fruit is!)
Oranges 2 = 2 full ice trays
Lemons 5 = 3 full ice trays
Limes 3 = 1 full ice tray
 
Thanks to Dr. Michael Greger for this recipe found in his How Not to Die Cookbook.