I would like to create a ghost material like this:
It's like in Blender Internal, making some complex material and reducing its alpha value.
But since Cycles is a physically correct renderer, I can't simply add a transparency shader – it always shows the inside of the object.
Here's my material setup so far. Simple enough, it's just a standard material where I want to add transparency. I saw some promising nodes, like Light Path with Transmission Depth but couldn't get any useful result so far.
Is it possible to get this result, without rendering in several layers and composing the picture later? If using this approach, I get difficulties with e.g. reflections.