In order to prevent filaments from absorbing moisture from the environment, you may wish to utilize a Drybox. This is a container that maintains a low/no moisture atmosphere to protect the plastic contained within. These are often homemade, as drybox construction is simple and straightforwards.

Most common filaments (PLA, ABS, etc.) will find little benefit from this system. Many other filaments require this system, as they can absorb enough moisture during a single print to ruin a print (PA, PET, PEI, etc.)

The enclosure needs to be airtight, and large enough to fit in your spool(s) of filament.

In order to remove the free water from the air in the enclosure, you need a dessicant. While silica gel is very common, it is “weaker” than many filaments, causing the filament to dry out the silica gel. It is recommended to use molecular sieves from a reputable supplier, as these are capable of removing almost all water from the environment, are reusable, and are “stronger” than 3D-printing filament.

While this is technically optional, monitoring the humidity in the drybox provides critical information about the health of the system. When the moisture level begins to rise, you can replace your dessicant to avoid having to re-dry the filaments contained within.

In order to print extremely hygroscopic filaments, the printer must be fed from a drybox directly.

This can be accomplished by adding a small hole to feed the filament through, which limits the amount of wet air re-entering the drybox. Typically, pneumatic couplers are used with PTFE tube to provide a convenient, reverse-bowden-esque system with which to supply the printer.

If you plan to add this feature, ensure you have a good solution for mounting the filament within the drybox, as tangles and fallen spools can be somewhat inconvenient to handle when the box is sealed.