I've bashed my head on this problem for awhile now. I've managed to work out a dehumidifier using a Peltier junction that can draw down humidity down to about 15% to keep humidity down in a sealed dry storage box.

I'm trying to scale the necessary performance for this thing. So far I can draw down a box that can hold 5x 1kg reels down to 20% fairly quickly (1hr starting from 55% RH).

Is this fast enough for most users? I don't know how often people pull reels out of their dry storage.

I think I can also make a version with oring sealed outlet ports so filament can be fed directly out the top of the box to feed your printer.

How much would you like to keep your filament in very dry storage ready to print?