How can you see the build for a polymock piece?

I found a polymock piece during the sneak peek weekend and I'm wondering how I can tell what the build will be for it. It is a Gaki and not one of the builds that is listed on the wiki. I can't identify the piece, it says that it's already identified. It has only one line of text, written in gold as if it is a rare: Gaki Polymock Piece. That's it. I would appreciate any help available.

Thanks in advance,

Aye