Got a cube and can select the internal edge loops easy enough with alt+right click. How ever the last loop which makes an external face won't select in the same way? What's the quickest way to select this loop in an editing workflow?
In cases of hard surface meshes like blocks, buildings etc. it's possible to select faces similar by normals or co-planar faces and convert that into the boundary loop.
- Select one face in the area around which you'd like to select 4 edge loops.
- Select similar faces of that area (use Shift+G > Normal or Shift+G > Co-planar).
- From the Select menu in the 3D Viewport header find Select Boundary Loop (or press Ctrl+E and find it in the list).
Note that this most likely will select more than expected once your geometry is complex enough (e.g. there are more blocks like this where faces' normals are pointed into the same direction etc.)
One more possible thing is to select edges by their sharpness. It's accessible through Select > Sharp Edges. Similar effect will have Shift+G > Face Angles.
Note that this will select sharp edges across all the mesh (above some threshold).
The quickest way to select a face loop is to switch to Edge Select Mode and select the four edges manually. Press Shift+Alt+RMB while selecting.
You are way better off to perform "pure" edge loop selections in Edge Select Mode anyway, because selecting edges won't automatically select vertices and thus whole faces.