To obtain the Yagudo headgear, you have to zone into the Altar Room of Castle Oztroja (the Magicite Area.) After a short cutscene with a goblin, go talk to a Tarutaru in the Windurst Clothcraft Guild. She'll tell you to bring two items and 20,000g for a cutting to make the Yagudo Headpiece. After giving her the items, come back the next game day. She'll give you the Yagudo Cutting.
Now, gather a Bugard Tusk, two black pearls, two yagudo feathers, wool thread, cockatrice skin, and the Yagudo cutting. This is the hard part: Find a clothcrafter (90+) with 60ish bonecraft and leathercraft. There are a few, Lizu I think is one; Overtaker, Barbatos, and Lughe are others. Of course, they'll likely ask for fees, but who doesn't?
After that, you can stop with the Yagudo Headpiece, or you can get a group of people together and pop the NMs in Altar Room and try for Tsoo Haja's Headpiece. Suggested party is, uh... a lot of bodies. Seriously.
EDIT: Right, uh. The synth is an earth crystal synth. Forgot to mention that.