It enables you to align objects where the centers or edges of their bounding boxes are lined up to one another. Tools For Design Using Autocad 2011 Autodesk Inventor 2011 And Lego Mindstorms Nxt Tetrix by Randy H. Boost architectural design and drafting productivity by up to 61 with features for architectural drawing, documentation, schedules, and drafting task automation. If each launch of AutoCAD shows the tools missing from the toolbar, see AutoCAD does not retain one or more. Re-add the tools to the Quick Access Toolbar and then export the settings for AutoCAD so that they can be imported if the tools disappear again.