One of the first project I completed has been building a 2 storey European building. To construct it I use 5mm forex that is easily cuttable. I draw the pieces on the board and then glued some floor textures I created with word. I am pretty happy of the final result although I did not attached windows and doors to increase usability with BA.
the upper floor
The ground floor and a particular of the stairs
The exterior and a particular of the roof