During the winter months in my house I worry about the same issue regarding humidity vs filament as we run humidifiers. These Ikea 395+ 10L boxes keep the humidity at about 20% as I have also put Silica Gel pellets hanging from the back to help with this issue.
Purchased cheap Hygrometers from Amazon (5 for $20) and married them up with an .stl from Thingiverse - Thanks @fardog! Here is a link to both:
EEEkit Hygrometer (Humidity and Temp Sensor):
Screw Mount for Dry Box :
The two nuts at the bottom are not needed as they are prep for the PTFE fittings and tubbing for a Lack Enclosure I am currently printing.
Thingiverse: Desiccant Bin for Filament Dry Box by gman10192
I don’t suggest this one as it gets in the way when removing filament in and out. My print the lid wasn’t tight enough hence the velcro strap…but it looks cool.
And here is a link to the Silica I puchased. 2lbs is alot!! buy 1lbs you could fill 6 silica boxes above.
Amazon: Indicating Silica Gel Pellets