Tarp boxes 2009-11
Perhaps you already know that plastic bags can be fused together—using a household iron to apply heat and light pressure—several ply thick? This forms a kind of tough tarp.
To make these boxes, which we've used to store our dishrags, we created tarp that is at least 8 ply thick. This gives it sufficient rigidity to hold its shape for storage boxes.
Happily, there are many instructions about how to create this tarp (on youtube and other such sites) so that I don't feel the need to elaborate more here.