Well, there was no progress for a few weeks, but recently I got into it again. I had nice few evenings with FreeCad (I'm total beginner in 3D modelling) and designed first revision of a case. It looks like this

Kind of classical, laptop-like case. Total size is 22x9x2,7cm when closed.

Unfortunately, it is two centimeters bigger in size than printable area of my 3D printer and I can't make it much smaller due to keyboard size. Time to get bigger 3D printer! :-)

I'll publish design files on Monday morning.