There is this deli owner who has covered everything with Oatly packages: Design by Bulent

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.

Ours go into the recycling. Not sure what they get recycled into. Have a vague memory of them getting shredded and mixed with resin to make insulation boards.

Some lessons on the use of milk cartons. We lazily did not clean all milk cartons and mice got through most of them. The mice at the cardboard with aluminum and plastic with the dried up milk bits.. one advantage, the milk has dried up. Now I have cleaned 134 packs and are going to use it to isolate the chicken coop I am going to build. Need 250 packs for inside roof of 3x3m. Will update you once one wall/roof has been built.