Originally Posted by
nsherry61
As I understand it, Mylar is metal coated plastic with the plastic being there to provide structure to the micro-thin metal layer. In the case of the wine box liners, I would think the metal layer is likely on the inside to prevent any plastic taste from leaching into the wine.
On a completely alternative note, Specialized Bicycles manufactures a series of water bottles that are called Purist(TM). These are a flexible LDPE plastic bottle with a micro-think layer of glass deposited onto the inside to prevent the plastic taste from getting to the water. It also reduces staining and bacterial build-up on the inside of the bottle.
So, as long as the lining is thin enough (a couple molecules thick?) and you don't mind using plastic as the primary structural material, it seems you can potentially get both collapsible glass and collapsible metal containers.
Good luck.