Box for temperature sensor based on ESP32 with BMP388 and with one 18650 battery. Code included. Data is uploaded 1x per 5 minutes to the tmep.cz server.

For this project you need:
1x 18650 battery. I used LG MH1.
1x Lolin D32 ESP32 board. They are cheap and great. The big advantage is the battery connector on the board. The battery can even be charged via micro USB but it won't be needed often because the power consumption of this unit in deep sleep is 80uA. So it lasts for years depending on the battery used.
https://www.aliexpress.com/item/1005005406866339.html?spm=a2g0o.order_list.order_list_main.99.379f18021JnGJI
1x BMP388 sensor
https://www.aliexpress.com/item/1005007050957586.html?spm=a2g0o.order_list.order_list_main.29.379f18021JnGJI
1x button switch
https://www.aliexpress.com/item/1005001513148147.html?spm=a2g0o.order_list.order_list_main.129.379f18021JnGJI
1x battery holder
https://www.aliexpress.com/item/1005006283625827.html?spm=a2g0o.order_list.order_list_main.191.1a9f1802nnsB4a
Hot glue, some wires, soldering iron, tin and 3D printed case, m3 heat inserts and screws.

After first start ESP32 will create an AP Wifi. You need to connect to it with your smartphone or laptop and login to your wifi via browser. Then it will save it. If the unit can not connect then it will create AP wifi again.

Enjoy!

You can ask me for anything in comments.

Martin