Here's a closer look at these inexpensive BlackMagic Design Cinema or Production 4K Camera cages. The unit is entirely made from metal and can be mounted fairly quickly to a BMCC camera.
The cage will allow dozens of new mounting points along the sides of the BMCC, but the top threaded plate may be too shallow to use with accessories. There is another version available that offers more mounting points in the handle.
Typically the cage requires the rail clamp to use a quick release plate, but in the video I share a tip on how to add a longer shaft 1/4 QR plate screw. Remember that this particular screw has a longer shaft, so it will be too long to use directly under a camera. Of course there are shorter versions of these screws if you want to replace all your Manfrotto (or other) screws into tool-less types. You can find these Extended Shaft D-ring Quick Release screws via eBay (Click Here).
D-Ring Extended Shaft Tool-Less QR Plate Screw