Background: Many 3D printer filaments are known to be hygroscopic, meaning they absorb moisture from the air. And yes, hyGroscopic is the correct term. It comes from a combination of greek terms for "wet" or "moist" with "to observe". Some people incorrectly use "hydroscopic" which refers to the use of a hydroscope, something that allows one to see underwater. If our filaments are ever "hydroscopic" we have more urgent problems than keeping the filaments dry...

Excess moisture can cause poor flow characteristics, voids, and brittleness in our filaments. Every filament I've purchased has contained desicant packs inside the vacuum sealed bags to absorb the moisture, but once the bag's seal is broken the filament clock is running. In some environments it might only be a few days before enough moisture is absorbed to cause issues. That's no problem if you're going to consume the whole spool immediately, but that's not the way I operate.

I've been storing spools in their original packaging until I need them. After partial use I then repackage them in a large zip-lop style bag and stuff them on a shelf. For a long time I used up the entire spool before changing to another to keep the logistics simple, but the purchase of an Automated Material System (4 spool filament handler from Bambu Labs) along with my desire to use different filament types for different purposes has fueled the need for organized storage and smaller batches. This requires a method to store and keep the open filaments dry for a far longer timeframe.

There are many dehydrators on the market. Most hold a single spool and have become relatively inexpensive over the last couple of years. I like the idea of preparing a previously opened spool using the dehydrator, but the hours it takes to dry means more wait time than I really want to invest in this hobby.

This project is to build a (larger than small) filament storage box with the ability to remove excess moisture from the air. I'll use a cold surface dehydrator to collect the moisture via condensation. It works much like the iced tea glass on my desk. I may also be adding a small heating element to the bottom of the box to provide a little airflow and a slight temperature increase to enhance the condensation capability. Experiments will be required to gauge the heater's effectiveness. I haven't seen anyone do it, yet.

The cabinet was inspired by an Adam Savage project on Youtube. I love his creativity and energy, but my engineering experieince and 9th grade woodshop skills might help deliver a more polished result to fit in with my office furniture rather than the garage.

Design Criteria:

• smooth finish in rich, dark, reddish brown (cherry?) or maybe a finish resembling metal
• top-hinged doors, plexiglass windows to see the labels, framed for weight to facility a tiny foam seal
• approximately 11 inches deep to sit out of the way and behind the office door
• three internal AC outlets (dehumidifier, heating strip, lights)
• shelves capable of excellent airflow that can hold spools or boxes
• shelf at the top for the dehumidifier (it makes cool air, so putting it at the top promotes airflow)
• room for the heater at the bottom (again, hot air rises)
• adjustable legs with rubber feet (it sits on a polished concrete floor).