Varavon has just released a new BlackMagic Pocket Cinema Cage w/ 15mm Rails. It's got all the features you'd need in a rig, including top handle and 15mm rail system. The red knobs seen at the front of the cage are used to 'clamp' cables in place from slipping out, such as the HDMI cable.
One unique option that I haven't seen with other #BMPCC Cages is the direct use of an LCD View Finder. In this image Varavon shows to what appears to be their Multifinder Uni Low Angle ViewFinder (though I can't be sure) attached directly to the BMPCC Cage. This ViewFinder will crop about 2mm on each side of your screen. You can already find the Varavon BMPCC Cage available via eBay (click here)
Varavon BlackMagic Pocket Cinema Cage with 15mm Rails HDMI Clamp