I came across this site that promotes a philosophy where everyone makes parts and components for everyone. They call it a cooperative economy where all from the small local artisan to the big multinational can contribute.
And as such they have a lot of plans and blueprints for both components and finished objects that can be made an readily reused in other builds when they are outdated or no longer useful to you. And all this interconnectedness is realized by a simple measurement OS grid found in the "How-to Manual".
www.openstructures.net/Enjoy
Edit: I also found this while looking into the subject of opensource constrution:
www.gridbeam.com/wp-content/up…Takes a while to load because it is a complete book.