If you employ multiple means on a regular basis, post the one that gives you the most satisfaction.
Also, please post the plans/designs for your defensive perimeter.
The purpose of this poll is two-fold: firstly, to get an idea of the predilections of this community, and secondly, to expand my own knowledge of dwarfish engineering/find inspiration for further exploits. I'm hoping this thread will lead to some constructive discussion on the subject.
Personally, I've only been playing Dorf Forts since 40d, so I'm rather new. Only recently have I attempted larger scale constructions, however, with the coming of DF2010 and the breaking of the military, I was forced to do so. My first construction was an attempt at a combination magma/water flooding chamber, trying to recreate what I'd heard of others making, but it ended in disaster, ultimately drowning, burning, obsidian-encasing, and then re-burning the entire map beyond reclamation.
My most successful design, which has reached MkIII status on my most recent fortress, is something I call "the flusher". It involves a 10x10 drowning chamber with drawbridges on either side, and a 4x4 retractable bridge over a 10-z-level drop to a large grated draining chamber. Above it are five z-levels of water cistern plugged by another 4x4 retractable bridge. When "The Lever" is pulled, the bridges raise, and the room floods almost instantly; once everyone inside is dead, the release is pulled, and the water swiftly drains, swirling the bodies and objects about the room not unlike a toilet before pulling everything below to be collected later. The design allows the chamber to be fired five times in quick succession without requiring any time to reload, and as I use a four-wide pump-tower design, I'm fairly confident it could operate indefinitely without ever running out of water.
For insurance, I placed a 3x3 array of weapon traps (each filled with 10 serrated steel discs) at the exit. Just in case. I prefer to use the drowning chamber because it's quick and, above all, clean. Buzz-saw traps fling blood and body parts everywhere, which is amusing, but unsanitary.
So, what about you?