Milk will expand when frozen but usually pushes the cap off.
Use about a cup of it before you freeze it. That way there’s room in the bottle for milk to expand.
I would not freeze it in glass. That could break and you’d lose all the milk as you cannot risk ingesting glass shards. That could kill you.
Use the plastic bottles.
I don’t know how the cardboard would work.
cardboard cartoned milk freezes well. The sides expand out a bit so it doesn’t stay square. Give it a little space around it.
Well, if the store has milk tomorrow, I’ll get more than usual and freeze some. Good idea.