That leaves a very important question: which is a better material for large serrated disks: copper, silver or glass?
Sadly Rocksinged only had a single goblin run into my new traps so far. They are all made of green glass, in 2x 15 layers, the first layer being "
Axe Blades, Discs, Corkscrews, Discs, Spikes, Discs ..." the second being the same except with
Spiked Balls instead of
Discs. It's a 3 tile wide corridor, all weapon traps are full with 10 glass weapons.
The result was that the goblin only made it onto the first axe blade trap. Even though the giant green glass axe blades
glanced away from his iron breastplate (and helm, I think), hits to limbs and especially the lower body were enough to kill him. Since all invaders tend to have some non-armored spots on their bodies, even if some attacks glance away on the armored body parts, they should still inflict enough damage to severly cripple any invader, if not straight out kill him (at least by quickly making him bleed to death).
In case they were to make it through the first layer of 15 traps, I can still flood the second layer of traps with magma - but I would rather have them run through those as well as there is a third layer consisting of 15 rows of cage traps. Pretty much something for everyone. I highly doubt anyone will ever make it that far though.
Still awaiting the next big siege with great interest, sadly in Rocksinged sieges seem to be almost as rare as the dwarven caravan and the outpost liaison - which have not come for years now for no apparent reason.
I would say, unless you expect heavily armored invaders - unlikely in unmodded DF, I think - you should be quite protected with green glass traps, as long as you don't win the lottery of bad luck, but I guess in that case you should accept your fate with pride...or have a military to kill the extremly lucky survivor.
Took me forever for all 900 weapons to be produce though, mostly since the sand is not very close to the magma glass furnaces.