Since the tower sides are symetrical, I just printed each side twice for the exterior and interior.
Of course the hardest part was the crennellated top. I glued this to heavy comic book or scrapbooking paper I got on line. And I used the same paper to support the floor.
Here's a photo of the completed tower.
Although it is not immediately apparent, the crenellated upper story lifts off as does the story with the arrows slots..
Here's the underneath of the tower top.
Was it fiddley? Yes! Is it perfect? No. Am I happy with it? Yes. It will do well in the game it is intended for. This is just a little advice on how to convert a quick build tower with no access to its interior into a playable tower with 3 floors.