How make my shape manifold? Substract one face from another? I'm quite new to Blender and I'm having difficulties with a geometry. You can see it here:



As you can see there are holes which I need to fill as I need this to be a manifold, solid shape.

I have managed to fill the holes by selecting similar and fill command but the result is this:



It creates two faces as if they were "concentric circles". For instance if I delete the largest face I end up with this:



But what I want is to have a face only between the "concentric circles". Is there an option to subtract faces? That way what I would like would be to subtract from the large face the smaller face.

Thank you!
You're looking for Ctrl+E > Bridge Edge Loops.