This is a Gridfinity Sony NP-F750 double Battery holder that fits in a 1x2 Gridfinity system. I couldn't Find a model for this so I decided to give modeling for a 3d print a try for the first time. Modeled from a blank bin found on thangs, just created the shape of the battery cut it out of that. Printed great for me, and the battery fit perfectly, so satisfying. 

Would recommend using magnets though because as you pull the last battery out its very easy for the bin to come up with it.