A built-in bookcase gives the room character and personality. If you are going to build it yourself, remember to think about the size of the different rooms in the bookcase and whether there are special things that need space, e.g. a lamp, a picture, the TV or perhaps a small writing desk? If the rooms are the same size, the expression will be calm, while varying sizes give a more dynamic, lively expression, and it will be easier to find space for your favourites.