Make space in your freezer for a large bowl. Fill the larger of the nesting bowls about 1/4-1/3 full of water.
Add the second bowl and weigh it down with additional ice or freezer-safe weights (a heavy bowl, more ice, etc.)
Tape the smaller bowl into place using craft tape. You want it to be evenly spaced in the middle of the bowl.
Add water to the space between the two bowls, filling until it is about 1/2-1 inch from the top, allowing for the water to expand while freezing.
If adding decorations, you can place them along the bottom and sides of the larger bowl before adding anything else (this works especially well for fruit slices). Or, you can add them after you’ve added the second bowl. Just place the fruits or flowers in between the sides of the two bowls before filling with more water (works well with larger flowers or plants).
Carefully place the bowls into the freezer. If needed, you can put it on a small baking sheet to keep it level. Freeze at least 12 hours or overnight.
Remove from the freezer and let the bowls warm up at room temperature for about 15-20 minutes. This should be enough to loosen the ice from the bowls.
Gently flip over and the bowl should slide out. At this point you can either place it back in the freezer until you’re ready to serve, or serve immediately by filling with more ice and drinks to enjoy!
Notes
You can add flowers or fruits either before adding any water, or after taping the second bowl in place and adding water, then moving the decorations where you want them using a knife or a long skewer. Both methods work fine!
If used for drinks, any type of decorations will work. If you are using it for food such as shrimp cocktail, make sure that all flowers and decorations are edible and/or food grade.
Do not overfill the water. You want to fill up to 1/2-1 inch from the top of the bowl as the water will expand when frozen. If it is too full, it can crack glass or plastic bowls. Overfilling can also cause the ice bowl to become difficult to remove.
Shocking the ice bowls by running them under hot water can cause it to crack, making it unusable. Instead, leave the bowls out for 15-20 minutes at room temperature. Since it can adjust the temperature gradually, it won't crack!
When serving, make sure to place the ice bowl on a large plate or serving platter. Empty any excess water as it melts. Adding a towel beneath the bowl can help to catch any excess water as well.