I have seen edible feathers done in several different mediums: rice paper, gum paste, or fondant. For the purpose of my cake, I used gum paste. Here are the items you need:
Feather Cutter (I used this one from Global Sugar Art)
Various colors of Luster Dust (Gold, Peacock Blue, Purple, Emerald Green, Black)
Real Peacock Feather to use as a guide for painting
Various paint brushes
Vodka/grain alcohol for painting
Also, you will need some foam or paper towels to lay your feathers on to give them some gentle shape as they dry.
1. Knead your gum paste with a little shortening to condition it and roll out fairly thin. I rolled it to a number 3 on my kitchen aid pasta roller.
2. Cut out feathers with a cutter. I find in works best to place your gum paste over the sharp edge of the cutter and roll over it with your rolling pin. I find doing it this way gives you a sharper cut then placing your paste on your board.
3. Place your feathers on your foam pad. On each side, starting from the center, pull out with your dresden/veining tool all the way to the outside edge. The goal being to add lines and dimension. Pull the tool out past the edges to thin and soften the tips of the feather.
4. You can also use scissors to snip towards the center very close together to give it a feather appearance as well . Here you can see what it looks like with one side completed.
5. Lay your feathers over a bit of foam or balled up paper towel to dry. You don't want the feathers too look flat and stiff. The foam will help make them look a bit more natural.
6. Now, here comes the fun part. Once the the feathers are dry, lay out your palette of luster dusts and a little bit a your vodka or lemon extract. Using your real feather as a guide, mix your luster dusts with a tiny bit of the alcohol and go to town painting your feather. I started from the inside of the feather and worked my way to the outside, using the real feather with its natural egg/oval shapes as a guide. Afterwards, I used a brush to try to blend the colors together.
The feathers on the finished cake.