Here's an idea for an architectural feature which may prove complicated, but have quite a pleasing function and appearance.
I have seen in some house building TV programmes people who have made walls that drop down to form an opening in the side of the building, and a floor to step out onto from this newly opened space... so the wall becomes a floor.
But instead of being a simple hinged, stiff board design, mine would be a segmented wall construction that would allow each piece to slide out, from bottom to top, to farthest to nearest the building in quite a groovy and sophisticated way!
My quick sketch outlines how this is achieved. By making the wall/floor out out progressively larger pieces of material (timber, for instance), the weight gradually increases with the size of the pieces, and so each piece is individually (and collectively with the others) a counterweight to the piece being moved at any given time. The numbers next to pieces I have drawn show the relative weight of each on when compared with the others... beginning at the bottom, where the weight value of this piece is the reference of 1 whole unit of that weight. The next piece above it is 1 ½ times the weight of the first, the next piece 2 times the weight of the first piece, the fourth piece 2 ½ times this, and lastly, the largest, and highest piece is 3 times that of the first.
This means that the small first piece has the accumulated weight of those above it pushing it out to it's final floor position when the catch is released, then the next piece slightly less, but having to travel just a little shorter distance to it's resting floor position, and so on, until the biggest, last piece, has only to move straight down.
Each piece, as it is moved in this way does so progressively slower than the previous too, giving a nice action to see, and is each piece has a spring which is compressed by the next arriving piece, then cumulatively this provides the mechanical assistance to return the floor to it's wall situation, as the largest piece would have the combined spring actions of all the other pieces to hoist it back up to the top in a straight line, and over a short distance, then, the next piece, slightly less, and so on, but all requiring only minimal effort from the user to operate the wall/floor in both directions.