Made from a big water bottle wrapped in several layers of cardboard. The whole thing is covered with brown paper, which makes the surface harder and look nicer.

The lid is made from 4 layers of cardboard and trimmed to tightly fit the container. When used, it's covered in a plastic bag for waterproofing

Shaping cardboard to tight tolerances is pretty easy: when dry it is suprisingly stiff; you can cleanly saw it through with a serrated knife, even at tiny shallow angles. You can also add more layers of paper to make it thicker.