ALUMINIUM soda cans are thin, making them easy to cut. They are light too and dent easily. So, how on earth do we cut slits onto the cans to make little lanterns without ruining them? The trick is to fill them with water and pop them into the freezer for a few hours. Six hours is quite enough for the ice to form before working on the cans. I left one can overnight and it burst open in one split!