This is a wrench organizer for my small metric open-end set from Craftsman (9-4308). I bought this set to keep near my 3D printer to tighten or loosen "all the things". I finally got around to making a tool organizer for it. Now the little wrenches are no longer wandering around loose looking to hide under the printer.
You can get your own matching set here: http://a.co/d/8FzMaRU That link is from Amazon, but I actually picked it up at my local Ace Hardware which seems to carry the Craftsman brand these days.