We drink a lot of milk and I have been collecting these bricks with the idea that there would be a usable function like isolation. But I slowly come back from that plan. the plastic inside will breakdown after a while I would think and there is no structural support of these packages. If I keep it empty, mice can nestle in it and filling with foam prevents from curing...
I am a bit out of ideas. Now i am thinking of using as insulation but then as a flat package. It will require only more milk drinking though ๐ . maybe you have some ideas to reuse these cartons?
That design looks more difficult to work with than the half-gallon and quart containers that we get in most of the United States (those are waxy cardboard rectangles with square bases and peaked tops), but a lot of people have used them for molds to make block-y things, whether literal blocks, candles, or something else. The waxy coating on the inside made everything easy to remove.
Those, though? As long as there's no smell left, I might suggest just using them for storage. They look well-made for anything from oil to beans, since they're not going to let air or light in.