Heloise has a trick that I have never heard of before, but is sounds like a dandy one!
Pearl Number Three
Rejoice you lovers of the frozen daiquiri! If you have freezer space tall enough to store a two-quart plastic milk carton... you're in business!
After you have rinsed out the plastic carton, fill with water and store in the freezer. When ready for that finely crushed ice, remove one or more cartons from the freezer. Next - and this is the trick - take the cartons to a solid concrete sidewalk or patio. Holding onto the carton, slam it against the cement on all four sides until it quits going "crack" and starts going "thunk."
Then open the top and pour out the finest crushed ice you have ever seen. It's amazing! This saves getting out the ice bucket too. Another good thing about this method is that you can pour out justas much ice as you need for your iced tea and drinks and then return the carton to the freezing compartment with the unused ice. It also saves filling those ice trays and spilling water.