Out here in California, we have a grocery chain called Trader Joes. They have 3 liter wine in boxes for under $10 U.S. I've drank all the wine and I now have an empty box with a bladder and a spigot. I'm going to put some film developer in it. Do you think it's a good idea? The bladder is made of a double layer of polyethelene. Here are some pics. Here's a tip. The black spigot won't unscrew. You'll have to pull it out of the plastic collar. It's also fun getting the wine box empty!