My son was like Thistle's boys. He built it the first time following the instructions then when it was broken down it was rebuilt into something different.
I put things in document protector covers and then in a binder when I use something a lot and want to preserve it like recipes, or children's project ideas. This way they can handle the wear and tear of continued use. Sometimes you can find the covers at the dollar store. Since they usually come 25 or 50 to a box at office supply stores it's not too much of an investment.