I know, there's lots of these, but I actually had intentions of making use of the hole in the front of the Sunlu dryer first, and then changed my mind.  I ended up putting one in the back instead, it worked better with my setup.

Printed in PLA and you have to screw it in place.

These are the hygrometers I used:

https://www.amazon.com/gp/product/B07MCGDN5C/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1