I have only done one mountbut it worked great!! Remove the "butt" like the others said
I fanned the tail out on cardboard, tacked it at the ends and traced the pattern of the tail. (this will give you a map of the fan)
Remove fan fromcardboard
Pull the fethers (start with the longest ones, side to side) from the tail and lay them out in the order removed onto the cardboard.
Use bondo to hold the fethers together.
Pull the next smaller fethers and lay them out on top of the first
another layer of bondo
and keep going untill you have the fan filled in.
When finished you just peel the cardboard off the back and can sand, screw.... the fan to any plack

Bennifits of this mount.
You have your fan mount in a day
You do not have to worrie about flys getting to it and ruining the entire mount.
If you have extra fethers you can replace or add in fethers for broken or damaged ones.

Go easy on the second, third..... layers of bondo so you do not have a 6 inch thick mount.