Plattform glued temporarily with 4 small blobs of white glue for installing of the 12 support arms. The support arms glued only to the platform, not to the tower.
It worked well: Plattform removed without mess. Will be separately primed and airbushed. Priming is necessary because the parts are made of thick porous and absorbent cardboard.
The lighthouse does not stand exactly horizontal but on a meadow sloping slightly to the sea (see next picture, Wiki commons) Therefore, I cut into the part represented the concrete slabs a hole.