I have found this to be more accurate than the round or rectangle hygrometers you can get from Amazon. After a while I got tired of having to constantly search the bottom of my drybox for it and designed a proper holder based on a good silica box I found, which would suit this purpose with fairly minor modifications (rescaling, slight reshaping, magnet holes and grips for counterparts). The four 10x2,5mm magnets need to be glued in place, make sure to align them correctly before that.

I've also included a print profile with negative cylinders instead of premade magnet holes, allowing you to scale them to accommodate magnets of any size.