Clipboard Case Pannier Hooks

Found a slim [plastic clipboard case](http://www.amazon.com/Dexas-1717-J104-School-Clipcase-Purple/dp/B009649T1C/) at Staples that fits a few of the things I often carry around in my bike bags (notebooks, etc). Modeled these hooks to turn the case into a compact clamshell saddlebag.

I've made the Onshape document public as [*Clipboard Case Pannier Hook*](https://cad.onshape.com/documents/da4f8a0bb0cb40748eff0ac2/w/e59eba1a5123488383fd2454).

I printed a pair of the `doxboxclip.stl` models t