have you tried weapon trap
Yes, I use these quite a bit. However the problem with those and the cage trap is there is an upper limit to the number of gobbos any particular arrangement can cater for whilst still encouraging them into the teeth of my fortress. I'm ever in search of a perfect design that will
a) kill goblins automatically, along with creatures the bring.
b) cope with an undefined number of creatures.
c) Require little to no military intervention. I'm just as prone to inattentiveness and fatal dithering as my dwarves are.
d) preserve loot for scavanging in an accessable place
This usually involves ways of plucking invaders off the main path of my fortress and into a pit of variable doom.
However the mechanisms for plucking and squashing are still work in progress. Sheer velocity has proven less effective than it used to be. My latest attempt left me with a pit full of water, dead dwarves and a broken drainage system.