How can it be made? 
Barbed Wire...
weasel
(weasel)
#2
Create a misc_model using models/mapobjects/military_trim/barbwire.mdc, and create a trigger_hurt the same size and shape as the model. The keys used in the other maps are:
KEY VALUE
------------------
dmg 25
sound sound/player/hurt_barbwire.wav
spawnflags 16
Drakir
(Drakir)
#3
Another way is to use the barbed wire texture and do a curvemesh. That´s what i did in the Rhine map. But you need a trigger_hurt as suggested above.