I'd like to say this is all my own work, but I can't saw a straight line, so the cutouts were done by my son.  But then I reckon that Adam would have had Patrick to help out!

In order for the house to have 5 bedrooms, a kitchen and a study as described in The Saga, I needed to have a double house, that is one where the front and back are removable.  This meant that the structural integrity had to come from inside walls.  Needing a big open plan living area also posed a problem.  The final decision was to put a corridor down the upstairs length with pillars supporting it - the walls there were then put together like a 3D jigsaw puzzle or like a wine box interior, each slotting into the other.  The first 3 pictures show this.  The kitchen staircase was a ladder style backed with corrugated cardboard.  The lighting in the top hallway and all its furnishings had to be fixed before the whole thing was put together as once the ceilings went on it would be inaccessible.