I love the idea of the rammed earth bird houses! I've got 3 kids, and I think that will be a fun project to do with them and learn to understand a little of the technique. My current plan is to use rammed earth to build a house once we find the land we want to purchase and settle down in. I like rammed earth because of the mass for energy efficiency, the beauty of the layers, and the fact it's not mold food. Most other building materials that I've thought about will grow mold if they ever get wet. That's a big concern of ours since a moldy rental house made us all very sick and still we are recovering. Thanks for posting! If you have any other photos of the bird houses or info on how you build them, I'd love to see that!