I have a US Authentic A-2 in goatskin. I like it a lot, but unfortunately A-2's aren't that warm and it doesn't seem like I get to wear it that often. I was thinking about looking into getting some sort of removable lining made for it (button or zip-out), possibly with something like Thinsulate. The main concern would be whether it would take up too much space. It's trim fitting, but I do have a little room. I can wear an extra zip up fleece sweatshirt or something like that with a normal shirt on and it fits. It's a little constricting in the arms, but not that bad. Has anyone had a lining like this made for an A-2? I'm not really concerned about keeping it authentic.