I do a lot of 3D printing in my makerspaces at home and at school. With a lot of 3D printing comes a lot filament (in FDM and FFF configurations) and that means I need a place to store it all. But you may wonder why should you use a special box to do this in the first place? Well, filament is sold in vacuum sealed bags with silica packets to ensure it doesn't absorb any moisture before use. Once you break that seal, your filament will start to absorb moisture until it cannot print effectively or even cause damage to your extruder. Signs of old and moisture absorbed filament include:

Increased diameter / will not fit through extruder
Jamming while printing
Clogged nozzles
Inconsistent extrusion and printing
Bubbling / smoking filament
Brittle / easy to break filament

From my experience all filament absorbs moisture, though at different rates based on type of plastic and even filament brand. I have found that dissolvable filaments (PollyDissolve, PVA, etc) are the worst and absorb moisture the fastest, ABS and Nylon aren't much better, and PETg, PLA, and TPU seem to hold out the longest. I've also found that the 2.85mm filament I regularly used on my LulzBot's lasts significantly longer than the more standard and small diameter 1.75mm filament which I only use from time to time.

Nonetheless, I wanted to create an effective and simple filament storage box so I would be able to have a handful of different filaments open at a time without having to worry too much about it going bad before I use them up. There are loads of filament boxes out there, as well as boxes that not only store it but have openings so you can print right from the box with a bowden tube. These are all great, but they were a bit complex and expensive for what I was looking for. I don't keep rolls out on my printers unless I'm printing, so I just needed a place to store rolls between uses. Thus this instructable! Through this guide, I will be sharing how I created my own storage boxes.

Supplies

I used the following for each box:

Plastic Storage Box with Gasket
Reusable Silica Gel Desiccant Packets
Hygrometer (optional, analog or digital would work)
3D printer and Filament (optional)
M3 nuts and bolts (optional)
Silicon Sealant (optional)

The optional supplies are if you want to add a gauge to monitor humidity as I did which is described in a later step.

Step 1: Choosing a Box

In order for the boxes to be effective, they need to keep moisture out. I chose these 12 Gallon Husky storage boxes from Home Depot because they come with a rubber gasket pre-installed, and I liked the clear lid with the snap hinged design. Each box stores around 12-15 1kg spools depending on the brand / spool design.

You could also easily buy some type of gasket tape or door seal to turn any plastic container into an air tight one as well.

Step 2: Humidity Sensor (Optional)

I wanted to be able to monitor the humidity level easily so I purchased a hygrometer. There are tons of digital ones available too, but I liked the battery-free simplicity of the analog one. I then used Onshape to design a holder for the gauge so it would be easily visible from the lid. Check out my Onshape tutorial series on YouTube if you're interest in learning more about this CAD program!

Next, I 3D printed the holder on my LulzBot Mini 2 using PolyTerra PLA. The design needs some supports on the base, I like printing these at a low fill density (~5%) for easy removal. After printing, it was time to pop the gauge into the holder and install!

The goal is to mount the gauge in a visible location while keeping the box as air tight as possible. First, I held the faceplate portion of the 3D printed holder where I wanted the gauge to be on the outside of the lid. I marked the holes using a marker through the faceplate, then drilled through the lid using a 7/64 drill bit. Make sure you put a piece of scrap material under the lid to avoid cracking the plastic!

Once drilled, I threaded m3 screws through the face plate and installed it on the outside of the lid. From the inside, I first put a small dab of silicon sealant on the screws where they passed through the lid. I then slid the holder / gauge portion over the screws from the inside of the lid so it sandwiched against the lid and squeezed the silicon sealant. I fastened this to the faceplate / lid using m3 washers and nuts.

Step 3: Adding Silica Gel Packets

Apart from an air tight box, the gel packets are the most important component of the project. Like the packets that ship with every roll of filament, these Silica Gel packets absorb moisture. The difference between the ones I linked here and the ones that come with filament is that the are reusable. This means that when they absorb as much moisture as they can, you can dry them out and use them over and over again. I like the packets I shared because they are color coded, the turn a dark shade of green when they cannot absorb any moisture.

I find that 5 or so packets works well per roll of filament, but this can vary based on type of filament and how frequently you open / close box. In general, I put 60 packets in my 12 gallon storage box for around 15 rolls of filament.

Step 4: Reactivating the Packets

Once the packets turn a dark shade of green its time to dry them out as they have stopped absorbing moisture. If you are using a humidity sensor, you will also be able to see your humidity gradually rise as they packets lose their effectiveness.

From the instructions in the wisedry packets I linked in this guide, you can dry them out using either a microwave or an oven. Personally, I prefer the oven method as I can dry out all of my packets at once without risking damaging my microwave from overheating.

Using the oven method, I set my oven to 250 degrees F and spread all of the packets across baking sheets. After baking for 10 minutes, I flip the packets over for another 10 minutes to bake on the other side (20 min total for 60 packets). The time can vary based on how many packets you put in the oven at a time, but I've never followed the times in the instructions exactly as I find that they are way too long and risk melting the packets (which I did once).

Step 5: Happy Printing!

I find that keeping my filament in these boxes extend the life of filament by months. In my classroom makerspace which stays at a pretty consistent 70 degrees and 60% humidity, 2.85mm PLA filament will usually last 3 months before showing any of these signs. When stored in the dry boxes between printing, I find that we have been able to print using a single roll without issue for 7-8 months.

Again, all of these figures will vary based on filament brand, type of filament, filament diameter, print and using conditions, and so much more, but hopefully these figures help guide you a bit in your decision making. As mentioned, there are loads of off the shelf solutions out there as well as many DIY guides, but I hope that you have found the simplicity and effectiveness of this guide to be helpful!

Thanks for reading and happy making!