Leave the mask somewhere you can find very, very easily, retire the fort, get a knife-wielding human adventurer, and get the freaking mask.
But.. but.. I love this fort.. I mean sure theres no metal to speak of on the entire map (besides maybe cotton candy), but at least I have sand and a volcano! WOO FOR GLASS! I have so much glass.. every 2x2 apartment has a green glass door, window, cabinet, and 'box', as well as the normal bed. My mayor's place is decorated entirely with green zircon encrusted clear glass furniture, which to say is a weapon rack, armor stand, two chests, cabinet, eight statues, two tables, two thrones, sixteen windows, and eight doors. All made by two legendary glass makers with a legendary gem setter for the gems (and a legendary gem cutter, but his skill doesn't addon to the value).