Help find the missing piece - A Community Puzzle

During my last visit to the library I noticed this scene:

I think I'm looking at a community puzzle. What an awesome idea! Deliciously low tech, yet an effective way to engage library patrons. I'll have to return to the library in another day or two and see if the puzzle is complete.

Hmmmm, I wonder how I could mash up this idea with the front yard library concept?