You can choose any container you'd like for the shape of your iceberg. If you want to sculpt your iceberg to make it more realistic use a balloon.
[header] How to make a mini iceberg [title] Gather the necessary materials. [step] To make a miniature iceberg, you will need a balloon or cup, water, food coloring, and a freezer. The balloon or cup will serve as the base shape for your iceberg.