Step 5: Arrange the Display
Place leaves, flowers and any other decorations in the water, wedging them between the bottle and the inner wall of the carton to keep them submerged. It should be a tight squeeze, and you may need to use the back of a utensil to shove them to the bottom of the carton. You won’t be able to see your arrangement through the carton, so mentally take note of what decorations you’ve already used so you have an even spread and variety of colors.
Step 6: Repeat
Once decorations are tightly packed on the bottom half of the carton, fill with more water until it is mostly full, and repeat the process with more decorations. The water will rise slightly as it freezes, so do not fill to the very top of the carton.
Step 7: Freeze It
Place on a flat, level area of the freezer so that the carton can stand upright on its own. Freeze overnight.
Step 8: Remove Your Masterpiece from the Carton
When you are ready to display the block, remove the carton by running it under cold water briefly. Pull the bottle out of the carton by the neck. If desired, chip or scrape small amounts of ice from the corners to give the block a rounded shape.