The Mountain Fortress
The plans are developing nicely. I'm not going into a lot of detail but I thought I would share some of the underlying concerns, and what sort of factors are used in determining materials and design...
First of all I should point out that I've paid particular attention to every stand-off from WACO to Ruby Ridge to Klammath Falls. I can tell you that there are things every one has in common, and there are very basic tactics that you have to prepare for.
First of all your fortress needs to be incredibily fire resistant. Burning is the favorite option of the government. A lot of evidence is destroyed, and they can always get their people to claim it was set by the occupants.
Any fortress is useless if it isn't largely self-sufficient. You need a secure deep-well, and alternative heat sources. Alternative power is something to have, but you should always assume you are going to lose it.
There should be 1 heavily defended entrance. Blastdoors are recomended.
There should also be a means of escape. Now this is tricky... because any way you can get out, they can get in. So this has to be something you added yourself, outside the standard plans. If you add this, you tell NO ONE about it. Idealy it would provide access to a route that could get you a long way away, without being noticed. Water is great for this.
I've seen people suggest building a home on an island in a river, and then stashing some getaway vehicles somewhere along the river a few miles away.
Not a bad idea... but I've been planning this for years... and I can assure you... mine is far more advanced.