The hard disk mount is to become a bathroom. The back wall will remain grey, but the side walls have cardboard inside as the metal had too many holes in it. The front wall, door and floor are also made of the same cardboard. There will be no separate ceiling for the bathroom even though it is a bit lower than the ground floor.
I had to start with the bathroom as it can be built as a module and then put in its place, but this has to be done before attaching the ground floor ceiling permanently.
The next picture shows what will be a shower corner. It is made of cardboard and the "glass" is part of a small mineral water bottle made of plastic. I'll probably put some kind of tiles on the walls and floor, but I haven't decided even the color yet. I'll also need to cut the door to the glass wall (I'm using tin shears to cut the plastic) and figure out what to use as hinges.
More about the bathroom later, next: Shelf unit