Multi-part fortress. Currently will just barely fit on replicator 2 when at original scale. You can use the crenellaitions as battle walls as well. Split between different layers, can make as tall or short as you wish, with the first layer being a normal bunker.
This started out as a paper project in pepurkura that I started, with making the files originally in CATIA. Finally got around to cleaning it up. I want to add an internal stair model later, so its marked as work in progress but you are otherwise good to go.