We had a problem with moisture getting into the filament. When I checked online for filament dry boxes, the price per unit was too high, so I decided to make one. There are some great designs available on the Thingiverse that use very little material, but I wanted something more robust with some extra features.

After three unsuccessful iterations of the filament dry box, I came up with this working model. I have printed nine of them, and they work great. The humidity in the room is around 45% but the internal humidity drops to 10 %. I uploaded an assembly instruction video alongside to help with the assembly.

I have also included a bracket that allows you to hang the filament dry box.

Part List

01 Container

The dry box is built inside 21 cup Rubbermaid food container. I have a link to the container attached below. I recommend searching in different stores for the best price,and if you find the clear one it would look even better.
Container Link

Updated Link Thanks to - @xerokillz

02 Bearings

The design uses four 608 bearings, below are the cheapest ones I could find.
Bearings Link

03 Mini Hygrometer

After finishing all 9 of the prints I've realized that they have the white version of the same Hygrometer. Keep in mind that those are not the most accurate, so expect a margin of error.
Hygrometer Link

04 Indicator Silica Gel

I like the indicator silica over regular silica, it's easier to know when you need to change it, although it's redundant since the design is using a Hygrometer.
Indicator Silica Link

05 PTFE ID-4mm OD-6mm

I used a tube with internal diameter of 4mm, this makes it possible to use the filament dry box with 2.85 (commonly referred to as 3mm) and 1.75 filaments.
PTFE tube Link

( Non of the links are affiliate links, I make no money from you using the links, use them as references and find the best deal in your location)