I posted a tutorial on making a Christmas tree out of old catalogues and gift brochures last year, on another blog. That post has since been lost, and I have recently been asked if I can resurrect the tutorial, so here it is!
fold over the top right hand corner of the first page, so that the edges are aligned.
now fold the same page again, so that already folded edge is now aligned with the spine
take the bottom flap …
and fold it under
so that your page now looks like this, with all the folds hidden
Repeat for every page. When you get to the last page, you can fold and tuck it around the first to help keep your tree together.