Amazing. Astounding, actually. I can only imagine the hours of work you have invested in this model so far.
One more question: How do you keep up your interest? I mean, personally I'm always gung-ho when I start a new model, but the longer I work on it, the more restless I get and wish I was further along... and usually I'll get to the point where I get bored with it and put it away and start something new. And too often that half-built model sits for years before I'll pull it out and work on it again. Sometimes I'll never pull it out again.
So how do you keep yourself motivated? Are you building this straight through, start to finish, with no other projects going at the same time?