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Something to build nooks/niches (e.g. shelves/cupboards that seem to be inside a wall rather than just in front of it).
Possibility to have borders on the top/bottom of a wall (skirting, kick/crown mold) Best would be if you could just move them up and down whereever you want them (middle railings are probably nice too and if you can stretch them they could work as backsplashes too).
Generally decorative architectural items (cornices and such).
Pools everywhere (e.g. on roofs while still having functional rooms in the stories below them).
Talking about roofs big variety of shapes and angles there would be nice