I am creating an atlas with multiple maps in QGIS. Each map is at a scale of roughly 1:12,000 and also includes an overview map at a scale of 1:200,000 in the corner which shows the entire region of interest.
QGIS Composer allows you to add an "Overview" (AKA extent indicator in ArcGIS), which shows the extents of larger scale maps within the overview map.
I am hoping to show the extents of all of the maps in the each overview, and not just the extent current map.
It doesn't seem like this is possible in Composer so I tried doing it manually by creating a shapefile of all of the composer extents for the main map from the project. Then I realized that there is no tool available to quickly generate rectangular features from extent values.
What method can I use to efficiently generate the overview indicators that I need, or polygons which could serve the same purpose?