Battery and SD Card holder for digital camera

Design this case to hold two digital camera batteries and some extra SD cards for traveling. I can't find a box or enclosure that will hold these securely and at a volume/weight that I like.

Dimension is 93mmx47mmx16mm, weight is 27gram.

The battery is Type X battery (my digital camera is Sony DSC RX-100).

The SD Card slot will hold 4 SD card.

Use suitable rubber band to "lock" it. I include the 123d files for tweaking to your battery size.