I use pieces of aluminum siding that I had laying around and formed them to fit and block the entrance into the pin box. I also use two mesh laundry bags got at the dollar store. I cut the bottom out of one and then pull it over the pin box and then put the other one over the front end of the pin box. I then use bungee cords to hold in place. When I went to take the 5er out of storage a couple of weeks ago the mesh bag at the back of the pin box was pulled down and the metal moved and there was a nest in there with three eggs. I just put the 5er back in storage used the same materials and bungeed the bags a different way, hoping that the wee buggers can't manage to get in again.