How? USE DYNAMO!
Why would you do this? Well... MEP spaces in Revit are 2D elements.
Its simply. Just follow the steps below (Also summarized in the image below)
Place these 4 nodes as shown and wire them up....
(Catergories, All Elements of Category, Element.Geometry, InportInstance.ByGeometries)
....you will see a 3D view of your Revit MEP Spaces in Dynamo and it will create 3D Objects (as symbol imports) to your Revit Model.
And Yes, Its really that easy to view and Create 3D MEP Spaces in Dynamo and Revit.
Don't know Dynamo? You don't need to, just download Dynamo and follow the steps above.