Day before using, make Ice Block: Fill a bowl with 2 quarts water, and let stand at room temperature 1 hour.
Stir occasionally to release air bubbles.
Mound 2 trayfuls of ice cubes in a 2-quart, fancy round mold; fill with the water.
Freeze until firm.
To unmold: Dip mold in warm water until ice loosens; turn out on waxed paper.
Return to freezer if not using at once.