How much to save? A question for my fellow writers

As I'm in the process of PACKING ALL THE THINGS, I'm taking a hard look at my collection of file boxes. For every book I have hardcopy of all versions, from the first submission through revisions, copyedits and galleys. That's a lot of paper, and I'm wondering if it's finally time to let some of it go.

So how about you? What do you save when you're done with a project?
[Poll #1792765]