This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.
From: <firstname.lastname@example.org> and <email@example.com>
I don't know if everyone else already does this, but I've started saving
the kit card, instructions, and a copy of the fin shape or shapes for
every kit I build -- rockets have a way of getting lost or broken, and
model rocket companies have a way of discontinuing my favorite kits.
Getting a color copy of the decal sheet (or better yet, a color scan) is
also a good idea.