Curiously, one of the biggest problems I've found has been the buttresses and once the levels are all completed, I think I shall have to have a good carving session with my scalpel to harmonise a few edges. I had expected the buttresses to be relatively easy as they are made from pre-cut wood and consequently all have the same measurements, but even though the card walls align, often the buttresses do not. The buttress on one corner in particular, on the second level, is at least 3mm out of line with the first and third levels.
Level 3 outer walls; I made a massive mistake and put these walls in upside down. This meant I had to adjust most of the windows. Level 3 is meant to be a 'great hall', so the level is 10mm taller than the other layers and will be dominated by one large room. I have already revised my design for this level three times since I drew it up and I'm still not sure how I'm going to do the internal walls. The problem lies in balancing between a realistic model and a model which can be used for playing skirmish war games. Some compromises are necessary and its always fun to work around the requirements of the games.
Level 4 outer walls. The story so far. Level 4 is the Lord of the Castle's apartment and will feature two toilets! It is the last internal level of the main tower, whilst the turret will have one more level to form a higher vantage point for the guards as well as a means of accessing the battelements. I also have an idea of building attachable hoardings to sit above the entrance.