While the original Arduino + ethernet case is great if you have - well - an arduino with an ethernet shield, there is quite some space wasted if you do have the newer arduino ethernet.

This case has been lowered to leave space only for the arduino board. I haven't tested whether or not the POE module fits inside...

Also, this case has added 5mm mounting holes on each side along with holes for 2 DB9 connectors which I had the need for.
The .skp files is included along with .stl files of each part (lid and case)