Xiaomi Mijia Bluetooth/Zigbee thermometer AAA batteries extension

Those little Bluetooth thermometers from Xiaomi can be flashed with custom firmware to turn them into Zigbee devices. But Zigbee implementation consumes a bit more power and a small CR2032 battery may not last too long.  

This model replaces the original back cover to fit two AAA batteries. With this modification the thermometer should last roughly 5 times longer comparing to the original CR2032 battery.

The model is designed to be printed without supports. It features plastic springs to put constant pressure on battery contacts. 

The assembly requires some patience, couple of wires and a pair of tweezers. 

This extension connects to the thermometer body with small latches. It easier to fit it without batteries and help the latches with some screwdriver from inside.

The modification is completely reversible as it does not require soldering to the device.

Additional STL for a skin modifier is included to allow enabling fuzzy skin in your slicer. 

The source FreeCAD file is also provided.