Orgnum's Scales is part of the base game. The crafting station is located in the Earth Forge. You can access it via a portal located inside a Fighters Guildhall, depending on your alliance. Portals are in Reapers March (Rawl'kha for AD), The Rift (Riften for EP) and Bangkorai (Evermore for DC). You gain access to the Earth Forge after completing the main Fighters Guild questline. You can craft any armor, weapon or jewelry of this set in any motif style you know, as long as you have 8 traits researched (per item). You can trade crafted pieces to other players. Each set item becomes bound on equip.