I put myself through college as a pastry chef, and continued to do wedding cake$ until my wife (7 years my junior), finished grad $chool. While I was a full-time pastry chef, one of the things I most-enjoyed and found incredibly gratifying was making gingerbread houses. In the commercial setting, these were for holiday displays, and they really were more along the lines of gingerbread palaces, castles, or mansions. There was no extra money in making them for me (other than extra hours on the clock), but they sure were fun. I can see how building these extreme bird houses would satisfy that same artistic need in a big way, AND the work product survives beyond the holidays for people to enjoy for many years.