Simple case for ESP8266 wemos D1 mini. With the micro usb connector. Just drill holes for temperature or SW420 or flame sensor wires. Hangs from wall plug. Uses two 2mm x 8 screws. Uses a small amount of filament and screws.

As shown in the picture a DS18B20 sensor is attached. I find that if the temp sensor is closer than about 5 inches to the ESP it is affected by the heat of the ESP.

Like my other cases, it hangs from the 5 volt power cube on the AC receptacle;

ESP8266 https://www.thingiverse.com/thing:6532569

D1 mini https://www.thingiverse.com/thing:6546733

ESP8266 with RCWL https://www.thingiverse.com/thing:6544638

D1 mini snap case https://www.thingiverse.com/thing:6547710