After seeing an Instructable on how to hand craft a batarang from the video game Arkham Asylum (http://www.instructables.com/id/Batarang-from-Arkham-Asylum-Game/), I realized that I could print one almost as large and definitely quicker than I could construct one from plexi. So here is a (partially) foldable batarang. Note - use of the batarang will not give you crime fighting powers nor is it likely to return to you after flinging it (although it did spin nicely).

I made this using Rhino3D 4.0, basically recreating the shapes posted on the instructable by creating a heightfiled (displacement map) and getting the contour lines, then using a loft between two similar curves to get the edge rather than having to cut a bevel. For some reason the holes in the mesh didn't print (even though they look fine - something weird about how Rhino handles mesh holes), so I just drilled them out, used a spare 3/16 machine screw, nut and two washers for the central pivot (which doesn't pivot very far) and partially drilled two 1/4" holes for 2 1/4" rare earth magnet thats fit flat into the wings at this depth.