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 😅. maybe you have some ideas to reuse these cartons?