LEGO The Hobbit

For this achievement you must first collect all of the 250 mithril bricks located around the open world and from completing the 16 story levels in free play. Also, you will need the 32 schematics to be able to forge the mithril treasure items (these are also in the open world and level).

Fast travel to Bree on the right side of the map and head into the Blacksmith shop, form there select a schematic to forge and play the mini game to forge an item. If you hit the buttons on the outer circle you will forge the item but, if you hit them in the inner circle, you will forge a perfect mithril treasure item.

Repeat this for all 32 items to get the achievement. If you forged them all perfectly the first time then this achievement will pop at the same time.