Bird nest in pin box

I had a small piece of indoor/outdoor carpeting left over from one of my 'projects'. I drilled some holes into the steel pinbox framework and (using some steel washers and self tapping screws) fastened the carpet to the pinbox so that it was completely inaccessible to birds. It worked well!

I put a small board over the opening one year and a rolled up towel in there that took up the entire inside of the pin box.