You know Styrofoam: The flimsy white stuff that holds soda pop at picnics and Chinese takeout, that's supposed to last for thousands of years in landfills because it doesn't biodegrade. It's so ...

Tall Styrofoam box with no holes in the base, plus its lid (or a panel from another box) Three 100mm lengths of 50mm-wide PVC piping ; Knife (sharp, pointed) Bamboo skewer (about 300mm) Measuring tape ...