Follow the link to a website with some creative ways of incorporating recycled glass and PET bottles into building structures. via Plastic Bottle Homes and Greenhouses Experiment with a small structure like a propagating shed...and then get a little more ambitious.
Actually, I've seen bottle houses, where there were hundreds or thousands of glass bottles cemented together on their sides to form walls. It looks cool on the outside (all the bottle bottoms), but it looks MUCH cooler from the inside, and this made the walls about a foot thick (wine bottles), so it was well-insulated.
