I found a model of a bracket suitable for thermometers and hygrometers, but the STL file I found somewhere was unusable due to a lack of airflow.

I've already modified the bracket to ensure the necessary airflow.

In addition, you need a standard 44-mm thermometer, just like this one:Goxawee 50~70°C/ 58~158°F Mini Embedded Thermometer - Made in Germany by Temu

Goxawee requires a 103% zoom for printing, and for some other models, it's best to use a 101% zoom for printing.

Last but not least, an LR44 battery is needed.

Enjoy it. For the person who created the initial STL file, I hope you're satisfied with this modification.