Uh, that may be overkill.
Here's a demonstration I'm unsure you can see, based on
this. 11 diagonal traps being enough to make entire siege dodge off, as long as they don't get provoked and become able to climb.
You should expand the gap size in shooting galley; 1-2 tile gap they can just jump over when provoked to do so.
I like the application of retracting bridges.
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Personally, when making trap defences, I favour layered approach utilizing certain elements:
‼: few cage traps followed by few weapon traps
#: building destroyer trap,
§: guard animals on chains.
I've also previously included:
ï: shortcut with trap for trapavoid thieves
^: Some kind of method for mass-killing a siege
Smaller reveñants in 47.04 may be an issue for this. Trapavoid but not building destroyer, they'd skip through first 2, and instead of going to the animal (and dying) they could just gesture to kill it through a window. If they come with a siege announcement, ^ can take care of them, but otherwise might need to add a pressure plate under guard animal that'd lock them in when animal dies.
ï had the issue that
"Kobold baiting" revealed forbidden doors to be useless as far as shortcuts go for those. Nowadays, this has renewed use; simplest would be to use obsidian-cast drawbridge to filter out your citizens from visitors/invaders/animals. If you lack magma for that, citizen-triggered pressure plate opening a hatch would do.
^: For killing method, I've done several minecart bumper and hitting traps alike (
"Soldiers are overrated" has good presentation.).
Water trap could be incredibly compact as well.
After several sieges, I think trap design should also consider disposal of corpses, so setting up a magma mister with few minecartfuls of magma might be good way to remove loincloths and corpses while keeping metal and artifacts intact.
If full disposal is desired, the old & simple atomsmash repeater would work.
Though these days, I favour using military, for several reasons:
1: I'm going to have a substantial military anyway, due benefits to work and happiness alike from cross-training.
2: Walking into a perfect trap and dying gets boring after a while. A killing method that makes fireworks of blood and corpses is much more fun, and sieges are even more interesting when your dwarves die in them.
Simplest disposal would be either fighting field being a drawbridge or having 1x1 pit with drawbridge below to throw corpses into next to field.
Maybe eventually it'll grow boring too?