This mount can be screwed to the inside of a drybox or glue some magnets to it to mount to the printer. These were the Hygrometers I used. I left the back open to maintain good readings. https://www.amazon.com/dp/B0C5SWVJ21?psc=1&ref=ppx_yo2ov_dt_b_product_details

I have incl F3D so you can adjust the size to fit yours.

Edit: Added an STL with Magnet Mounts for 8mmx3mm Neodymium Magnets. The Magnets work great because there are no holes in the drybox and I can move the Hygrometer anywhere I want.