This hook was designed for the purpose of hanging a garden trellis net from a cable, but probably has applications elsewhere. It was designed to have a very low poly count and straight lines for fast slicing and printing.
While this hook isn't limited to its application in the garden, you can find a little bit more about its application and more of a write-up with some info on a couple other printable garden accessories here: http://www.protoparadigm.com/2012/05/what-to-do-with-a-3d-printer-make-garden-tools/
The scad file is parametric, so you can adjust the overall length, the gap (same on both sides), and the thickness of the hook.
Print and enjoy. Good luck with your beans, peas, and other and other climbers.