I'm also saving almost all the envelopes I get for the stamps. Lately I have done it less, though, because my apartment is so small that I don't have room to collect all the stuff that I want to save.
I should have a bigger apartment just to fit all the crafting stuff that I would love to save/buy in it. I'm a bit of a pack rat when it comes to paperstuff, fabric and yarn.
But I think it's a good idea to make ATCs of all the collected paperthings that has been saved.
Ditto! My hubster and I also live in a small apartment, and my crafts are consuming the entire apartment. I have a room in which I keep all my crafts (and book, omg the books) but then right now my dinning room table the living room are just a mess w/ crafts! I'm a messy crafter! Being in three swaps and an ATC swap has not been kind to my apartment. This morning I just collected up all my envelopes and clipped off all the stamps from the ATCs and put them into a little container. Yay for a little less clutter! I haven't had to buy anything for the ATCs I've been making.