I've made a Drybox storage solution for all of my filament. This box is from Iris and it's airtight and dust free. This box is L39x29Wx26H and has the capacity for 20L.

You can store up to 4 rolls of filament in 1 box (1KG each). I also made a hole in the front of the box and inserted a Hygrometer/Thermometer. On the back i've sealed it with tape so it's still airtight. You could also use something more permanent. In Each container (3 in each box) you can fill each with 40gram Silica Gel Desiccant. The humidity in the box went down from about +50% to 15-20%.

I've also made a label for the lid so you can insert the correct Filament labels. This should be published soon.

The file:

2 round bars. Support normal and 3 walls for strength.

3 lids: Support Tree Slim and 2 walls.

3 trays: NO support and 2 walls.

2 connectors between trays: Support normal and 2 walls.

There's also a Funnel. You could delete this if you don't need this for filling the trays.

Assembly:

The bars are tight at first, Use the middle lid (both sides open) and twist the bar multiple times through the hole (don't forget the ends). This should make them fit a bit easier. Insert the bars through the middle lid and then connect both ends.

You can push both connectors between the trays (do make sure you keep the same top/bottom orientation as the print so it's nice and flat)

Now align the lids with the trays. When they're aligned you can fill the boxes with 40grams of Silica Gel each. You could use the silica funnel for filling. The sides are easy to fill but the middle might be a bit more difficult without spills. When you fill the funnel you can tap it a few times and move it over the middle of the tray.

You can now attach the lid back onto it and put the whole assembly into the box. Enjoy!

For the Hygrometer i've drawed a template on the box and used a soldering iron to create a rough hole (do make sure you use it outside because it might smell a bit). Then used a flat file to make it fit and round the edges. At the back of the hygrometer (on the inside of the box) i've used tape to seal it, For a more permanent solution you could also glue it.

Sources:
Iris box 20L: https://www.iriswebshop.eu/air-tight-box-20-liter-set-van-3-copy.html
Silica Gel Desiccant: https://www.amazon.com/wisedry-Gram-Packs-Silica-Packets/dp/B01MPYB16J/ref=sr_1_3?crid=4X2ZSW7IE7GU&keywords=wisedry%2B10%2Bgram%2B30%2Bpacks%2Bsilica%2Bgel%2Bdesiccant%2Bpackets%2Breusable&qid=1704552922&sprefix=Wisedry%2B10%2Caps%2C147&sr=8-3&th=1

Hygrometer: https://www.amazon.com/Thermometer-Hygrometer-Temperature-Fahrenheit-Greenhouse/dp/B08RLZ3SL9/ref=sr_1_4?crid=C8E4GABN2DDQ&keywords=vaikby&qid=1704552994&sprefix=vaikb%2Caps%2C160&sr=8-4