Kill Zzarc'Vul in the southern ogre mound in Duskwood and collect the Ogre Monocle.
Now there is just one more item needed to complete this device. Cog's blueprint calls for a lens of some sort. The only lens I know of that would be large enough will be very difficult to acquire.
There is an ogre by the name of Zzarc'Vul who resides in the mound in southern Duskwood. If you can, bring to me his monocle and I will use that as our lens!