Did you test the reception of gsm signals with the alu back cover? How is the signal reception for 2g/3g. Better or worse than with plastic cover?

The way I see it. Most manufacturers have only on one side metal. In the at least 2 dimensions they have non-metal where the antenna is. See iPad with lte or the HTC One with plastic end caps.

On another note. I discovered that there is a scan machine at the uni lab where I can scan my device in fro free. How accurate does the scan have to be? Is there a format it should be in to be imported in autocad or some other cad program? And if I scan every part independently, is it possible to combine all this parts later in a cad program?