I used to lay my fans out on a piece of cardboard and put pins in them to dry em out... JWs idea works better cause its durable and you don't have to worry about losing the pins...
Lately I've been using an antler thats big enough in mass so that it both will keep the fan spread out and also keep it from pulling itself up. I just put the center tine in the antler where the tail attached to the body and then spread the fan so that the other two tines on the antler spread the feathers, then just propped it up on something... Shown is this years bird. I ussually let the fan dry for 3-4 weeks, then I mount it.
