Wikihouse is an archive of open source building designs contributed by engineers and architects around the world. Each design is peer-reviewed and analyzed by others to ensure that the designs are sound. Some of them have already been built and the results posted for further review. The design principles include being as easy to build by people with minimal formal training, as energy efficient as possible, and easy to modify to fit a particular purpose. All designs are made in Google Sketchup and can be cut with an automill if available.