update 2011/08/02: please see comment by TIm O’Reilly at the end of the post Instructables is a web-based service created to “enable open-source hardware by [allowing] users to collaboratively design, document, build, and market their ideas”. Instructables was just acquired by Autodesk, the world leader in 3D design and engineering software. Autodesk believes that this move “will assist makers of all types by linking Instructables’ vibrant online community to Autodesk software tools and services”.