Sonoff temperature sensor battery hack

Sonoff Zigbee Temperature Sensor SNZB-02 battery hack to replace the CR2450 battery with 2xAA batteries.

You also need the [CR2450 battery eliminator](https://www.thingiverse.com/thing:6480507) and a 2xAA battery holder. You can use [Flexing Battery Holders with Integrated Spring by Pixelle](https://www.thingiverse.com/thing:2339441) with the `sonoff_temp_battery_hack_..._printed_holder.stls` or a ([commercial battery holder like this one on AliExpress](https://www.aliexpress.com/item/1005006225310014.html)) with the `sonoff_temp_battery_hack_..._commercial_holder.stls` - or you can edit the openscad file and adapt the battery holder dimensions, e.g. if you want to use 2xAAA instead.

The box can be printed without supports, I used 10% infill.
The lid needs supports, I used 15% infill.

To assemble:

- If you printed your battery holder: insert wires as shown at [Flexing Battery Holders with Integrated Spring by Pixelle](https://www.thingiverse.com/thing:2339441)
- Solder b