Could not be simpler or more straightforward; holds two Sony NP-BX1 batteries that are used in a range of recent cameras.
I have provided the Rhino3D design files in case you want to tweak the design.
RX100_battery.stp | 492.5KB | |
RX100_battery_holder.stl | 5.1MB | |
Sony_RX100_battery_holder.3dm | 3.8MB |