I decided to make my own Minas Tirith using extruded foam and Styrofoam. I had commissioned The Castle Works company to build me one, however he backed out in the end and took my $2500. Out of anger, mostly because I really really wanted a Minas Tirith...and the fact that I just painted over 2500 Lord of the Rings figures to have the Battle of Pelennor Fields, while I was waiting for it to be built. I was promised it would be made in 6 weeks...two years later...no Minas Tirith. I made this Minas Tirith in 7 weeks. I cost about $1400 roughly. And I worked 50 hour work week while working on it. I used also some Games Workshop Minas Tirith walls, because I liked them and it gave me an excuse to buy 3 sets. Anyway below are pics from start to finish. It is a bit pic heavy, but I wanted to share how I made it, in case someone else has the crazy idea of making one for them self. I used the tools from the HotWire Foam Factory.
I also designed it strictly for playing, not really a diorama. It is modular and easily stored on the shelf. It is also made so that it is easy to put the minis in the fortress as well.