"I'm not sure. Possibly a pentagon, but it might take a hex - I don't know how Elias did the secret room, but I don't need quite that much sophistication necessarily. I don't want them in my backpack, though. They have to be touching me so I can use them, and I'd like them accessible in an emergency - if my car skids on the ice, I want to undo that right then, rather than dig around for a square in my bag in the backseat. I need a necklace or a bracelet or something."