Cases will generally work if the back is less than 4mm thick, the front is less than 3mm, width is under 70mm wide, and a standard apple cord can plug into them on the bottom.
Cases tested to work: Apple Bumper, Element Case Vapor Pro, Incase Slider, Snap and Feather, CaseCrown Glider, Elago Breathe and S4, Incipio Feather Ultralight, Speck Pixel Skin and CandyShell.
Cases that don't work: LifeProof (hard plastic bottom door is in the way).
The Otterbox Defender and Commuter will work if you snip it off the bottom rubber flange with scissors.
If you really want your OtterBox to work with the flange, we will mill you out a dock with a larger opening to accommodate it. We will give you this option when the funding closes and we verify everyone's order.