I've got a plywood silouette but have never used it. If you time things properly, use another dog and a remote release trap. What you need to do it bring the backing dog in from where it can't see the pointing dog and the moment it looks at the pointing dog, pop the bird. Don't teach it till the dog is pointing and holding very well.
My present dogs are the only dogs I've ever had that did it naturally from the start, e. setter's. I've had a lot of shorthairs and pointers and they all got it really fast.