The decision to use the machine room as mancave was not really a change for the build.
The machine room should looked the same anyway and that's one of the reasons i changed the plan.
Simple as, it would be to nice as machine room.
First wall to tackle was the wall against the storage.
I bought OSB board and cut them in 40cm/16" strips each, much like wallpaper.
MUCH easier to handle such a strip than a whole boards, especially when there is lots of cutting involved.
The first wall is made of five strips.
First strip up
Five strips cut, mounted and done