The CAME-TV GH-4 Cage is designed specifically for the Panasonic GH-4 and provides easy access to the battery and SD card without actually removing the camera from the cage. The baseplate that comes with the CAME-TV GH-4 Cage has 15mm rod holes that allow you to attach industry standard 15mm rods for accessories like a follow focus.
(Geekynerddad's GH-4 setup with the CAME-TV GH-4 Cage +Wooden Handles)
Click below for more information on the CAME-TV GH-4 Cage.