1. It had to be UNIQUE. Something that you would never think of for a birdhouse.
2. It did not have to be functioning, but it did have to be hollow and have a bway for the hypothetical bird to get into the non-functioning house.
3. It needed to be about minimum of 8 inches.
4. It needed to be made out of clay.
With those being the only requirements here are some of the final results. Overall they have been very creative. Here are a few on the best examples that are done. I will add a few more pictures when the rest get done.
I am not sure you would be able to convince birds to live in some of these even if they were good sized.