I've been watching a bluetit carrying nesting materials to the birdhouse in our back garden. Hopefully he'll attract a mate and raise a clutch of chicks like last year. Here are some images I found when searching for "recycled bird house". Each image is a link to the page it comes from. Some of them have instructions how to make the item, some are ready-made items for sale, and some are out-of-date and no longer for sale, but I thought they could be inspiration for your own recycled bird house projects.