I'm new to this thread, but have been an ATC making and trading addict since last January, and thought I'd share a technique: using recycled magazine pages (nope, not for cutting and pasting pictures, but for making coloured strips of paper with all kinds of patterns).
How does it work?
You tear the coloured parts of old magazine pages into strips (could be any part of a page, for instance a picture of a person, of flowers, of a building, a road, of textile, advertisements, backgrounds, etc.; just look for pretty colours and interesting patterns). Then...
1. You can use the strips as they are, on a cardstock background, like this:
2. You can glue them on a piece of printer paper, draw a silhouet on the back, cut it out and glue that onto cardstock:
3. Or you can combine the two, and cut a white border around your silhouet:
4. Or you can simply use the coloured stripes as a background.
(I made several of those, but haven't photographed them yet.
I don't want this post to be pic obese, so if you want to see more examples, check out my Flickr ATC set:http://www.flickr.com/photos/made_by_beag/sets/72157625790653892/
For glue I use Pritt sticks.
And be warned: this technique is highly addictive and once you have tried it, you want to tear up every magazine you see (which could get you into trouble)!
PS: as you probably already noticed from the pictures: magazine printing is hard to scan! I now started photographing instead of scanning this type of ATC's.