Q:

QGIS - Creating a new polygon layer from the space between other layers

I wonder if it´s possible with QGIS (2.18) to create a new polygon shapefile directly from the space between Another 2 different polygon layers:

What I would like to do is to fill the gap between the two layers with a feature of a third (new) polygon shapefile. It can be done digitalizing the borders, but If there is a way to do it automatically, I could save a lot of time.

A:

You can use following workaround where I used layers of next image (with a space between them):

Merge layers with Data Management Tool -> Merge vector layers.
Get polygon from layer extent (merged layer) with Research Tools -> Polygon from layer extent
Get difference for extent and merged layer: Geoprocessing Tools -> Difference. My result was:

As this layer is Multipart it must be converted in Singleparts: Geometry Tools -> Multipart to singleparts.

Select central feature (hole) in singleparts layer and intersect it with merged layer extent (Geoprocessing Tools -> Intersection). Result will be desired layer (hole); as it can be observed at following image. 

