Forget the Cocktail Ice Spheres, Just Freeze these Gel-Filled Glasses [Updated]
The only thing worse than a lukewarm drink is a watered down one. You can invest in cocktail ice molds (more on those shortly coincidentally), or just freeze these glasses in your freezer.

The only thing worse than a lukewarm drink is a watered down one. You can invest in cocktail ice molds (more on those shortly coincidentally), or just freeze these glasses in your freezer.
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Bonus: Bowls.
Update 12/1/17: Step up to the Rabbit versions for a much more premium look and feel.
Update 12/1/17: If you prefer ice over gel, the Corkcicle Whiskey Wedge delivers what you need in an elegant package, no ice ball molds required.