My friend saw a wall hanging of origami koi that she really liked, but the etsy shop that was selling it had it priced at over $1000. Thus, I set out to make this for her birthday/Christmas present, and after countless hours of folding while walking, an art that I have mastered, I finally finished the koi and attached them to the friend's bedroom wall.
UPDATE: I recently made another version of this complete with LEDs and rainbow lighting; just check out my projects page to find it.
I used online diagrams (whose link doesn't work anymore for some reason) and a stop-motion video of the folding process (http://www.mabonaorigami.com/en/videos/the-making-of-an-origami-koi.html) so have fun! It's pretty tricky, especially the swivel folds, but feel free to comment below if you have difficulties and I'll try to help. Fold as many as you want, but I folded 39 of them: 1 white, 2 bright yellow, 3 yellow-orange, 2 dark orange, 2 light orange, 7 red, 2 pink, 5 purple, 2 dark blue, 5 medium blue, 4 sky blue, 1 dark green, and 3 leaf green.
For people stuck on the swivel folds (the small folds for shaping the left and right sides of the fish), go to this link: http://www.instructables.com/id/Wall-of-Rainbow-Koi/
and see step 3.
On flat surface, arrange your fish how you want it to look on your wall. Take a picture and save it or print it out for guidance when you actually attach the fish to the wall.
To be honest, even though I did this step, I ended up winging the design. And I like how everything turned out so skip this step if you want.
I liked the final version, but I thought the koi looked too restricted to one area and looked like it fit a perfect rectangle even though there was plenty more space next to it. This being so, I decided to outline that imaginary rectangle with dark green yarn (no blue available). I liked this result a lot better so do this If you think it would help. If not, then you're done! Enjoy the new wall art!