How To Make a Dry Box for 3D Printer Filament Storage

If you have an FDM 3D printer then you likely have multiple spools of various colors and types of filament. You have probably asked yourself: How do I store filament? How do I protect filament from moisture? Proper filament storage isn’t only necessary for exotic filaments such as nylon or TPU. Even simple PLA will show issues if it is stored too long with humidity. The best way to store your filament is with a filament storage dry box. It is cheap and easy to build one yourself, read on for our how to guide.

Why Do I Need a Drybox?

3D printing filaments can be very sensitive to moisture, especially the more hygroscopic ones such as nylon, TPU, and PETG. Common signs of filament that has absorbed water are a popping sound when printing, massive stringing, weak layer adhesion, and a fuzzy surface texture due to underextrusion. If you have these problems then your filament has likely absorbed moisture and needs to be stored correctly.

Printing with a dry filament fresh out of the package vs an old spool that has been sitting absorbing moisture can be the difference between a good and a failed print. Storing your filaments in vacuum sealed bags with small desiccant packets is one option but it is very inconvenient. Follow our guide below to make your own filament storage dry box. For those tricky filaments like nylon you can even print straight from the box.

Shopping List

• A plastic bin
• Desiccant
• Hygrometer
• PTFE Tubing (optional)
• Pneumatic Coupler (optional)
• Metric Nuts for Coupler (optional)
• Spool Holder (optional)

Steps To Build a Filament Storage Dry Box

Step 1. Obtain a storage box

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The goal of this box is simple, prevent the intrusion of water. A plastic bin will be ideal, preferable one with a gasket on the lid. It should have latches to hold the lid closed and be large enough to fit multiple spools of filament standing vertically. A medium to large bin should be able to hold 5-8 spools of filament, smaller bins will only hold 1-2.

Step 2. Fill the box with silica desiccant

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You will need enough desiccant to absorb the moisture in this box over a long period of time. Those little packets that quality filament comes with, those are just to keep it out of a small bag. 2lbs of silica gel pellets should be good for a medium to large plastic bin.

Step 3. Install a hygrometer

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Silica gel has a finite amount of water that it can absorb. A hygrometer will help you know what is going on in your dry box. Mounting one on the inside of the box so you can keep track of the humidity in the box and determine when your silica gel requires replacement is a must. If you are using color changing silica gel then you already have a visual representation of what is transpiring but it does not provide specific moisture levels.

Step 4. Place your spool holders in the dry box (optional)

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If you intend to print directly from the dry box then you will need to have spool holders directly in the bin. There are a lot of options for 3D printing these. Automatic retractable spool holders are nice though a bit time consuming to print. A quicker and cheaper alternative is to print a bracket for each end of the bin and then use a large dowel to hold the spools. If this dry box is just for storage you may skip this step.

Step 5. Install coupler and PTFE tubing (optional)

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If you are printing directly from the dry box then you will also want filament guides. A simple solution is to purchase some pneumatic couplers and PTFE tubing. Drill small holes in the bin and thread the couplers through it then use a nut to secure. Insert a few inches of PTFE tubing so that there is a defined path from the spool and out towards the printer.

Step 6. Load up your dry box with filament

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Your storage dry box is ready, put your spools of filament in the dry box. The length of time that the silica gel in your dry box will continue absorbing moisture will vary based on the ambient humidity in your storage location. Watch for the color change in your silica gel and any significant trend upwards from your hygrometer.

Step 7. Recharge your spent silica gel (a few months later)

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If you are using a color changing and reusable silica gel desiccant such as Dry & Dry then you can recharge it. Set your oven to 200-250F (93-120C) and wait until it reaches temperature. Make a single layer of silica gel pellets on a sheet pan and place them in the pre-warmed oven. Let the pellets sit in the warm oven for 0.5-2hrs until they return to their original color. Cool the pellets and then return them to the dry box.