DIY Filament Dry Box: How to Build One on a Budget

What to Think About

Building your own dryer or dry box sounds daunting if you don’t know where to start. Like any other project, it’s helpful to come up with a plan based on your needs and expected outcomes.

When planning out the build, there are several design considerations you need to take into account. You need to think about the space you have available for a dryer or dry box and how complex you want this project to be. And although it’s ideal to keep all your filaments as dry as possible, some materials are more sensitive to moisture than others and should be prioritized. Therefore, there are a few key things to think about.

YOUR CURRENT SITUATION

Do you already have filament in need of dehydrating? Filament that needs to be actively dried determines whether or not you should use a heater or passive dryer. All filaments benefit from being stored with desiccant, while specific filaments such as nylon, PETG, and TPU should be dehydrated using heat when needed.

YOUR COMMONLY USED FILAMENT TYPES

How hygroscopic are your filaments? Finding out how moisture-sensitive your filaments are helps you to determine the potential conditions your box will have to meet to maintain those filaments. PrintDry, a manufacturer of dryers, has created a helpful table with specific temperatures and drying times for 12 different materials.

CAPACITY

How many spools need to be kept dry? One major benefit to building a dry box is that you’re only limited by the size of your box. The larger the box, the more filament spools you can store. If you opt for a dryer, scaling up gets more complicated, but there’s always the option to buy an affordable food dehydrator to dry up to two spools at a time.

CONVENIENCE

Do you want to feed filament to your printer directly from the box? If you want to keep filaments in the box while simultaneously using them, you’ll need to cut a hole in the box for the filament to pass through and find a way to let the spool roll. Because of this, consider how you’ll maintain the airtightness of the box and keep the spool rolling in place. If you’re happy to keep your box as pure storage and remove filaments for use, then really all you need is an airtight box and a few packs of desiccant!

Getting Started: Basic Materials

Now that you’ve come up with a build plan, we can discuss the basic materials that are constant in any dryer or dry box. These include:

• A storage method, usually in the form of a clear airtight plastic box, enclosure, or vacuum-sealable bag. It should be big enough to hold at least one spool. Be sure to measure the dimensions of your filament spools for reference, and consider how many you want to store and how much space you have available.
• A spool mount that holds your spools in place to dry uniformly. These can be rollers, rods, or even a custom 3D printed fixture. Depending on your chosen storage container, a mount may not be necessary, for example in a round container.
• A drying element that is either active or passive. If active, it will be a kind of heat source such as a heating fan or food dehydrator. If passive, desiccants such as silica gel, salt, or molecular sieve are used.

At a minimum, you can build a dry box with off-the-shelf components without modifying anything. Depending on your design considerations, there are optional components to upgrade your box, such as:

• Tools to cut holes in your box. This can range from a power drill to a utility knife, as long as it can cut through hard plastic without cracking it. Be sure to wear protective equipment such as safety goggles or gloves as appropriate.
• Tubing is required if you choose to feed your filament directly from the box to your printer. Ideally, PTFE tubes are threaded into the hole in your box (or through an adapter) to feed your filament while keeping the box airtight. As an extra advantage, this will protect your filament from the outside environment even between the box and printer. Note that the size of the tubing depends on the diameter of your filament.
• 3D printable parts if you’d like to design custom parts for your box, like a spool mount or box-to-Bowden adapter.
• Sensors to monitor the internal conditions of your box. The most commonly used sensors measure humidity, temperature, or both.

Basic Assembly Tips

Using the above basic materials, the steps to build a DIY dryer or dry box can include filling an airtight box with desiccant and placing the filament inside, storing filament in a food dehydrator and setting your desired temperature, or vacuum sealing filament in a bag with desiccant.

However, these assembly tips are applicable if you choose to modify or upgrade your materials:

• Conduct fit/motion tests: Dry boxes that will feed filament from box to printer require smooth rods, rollers, or even bearings to ensure the spool rotates smoothly. When your mounting system is assembled, place a spool on it to simulate the feeding process.
• Think twice, cut once: Ensure the holes you cut or drill aren’t too big. Consider drilling a slightly smaller pilot hole in the initial run, and then conduct a fit test. If the hole is still too small, you can progressively make the hole bigger and repeat the fit test until you achieve the perfect size.
• Test for consistent dryness: If you choose to include sensors, test them out throughout the build to verify that the inside of your enclosure is dry and temperature-controlled.

DIY Options

There are many DIY projects that have been tested by the 3D printing community to prove their effectiveness. More importantly, the DIY approach allows you to customize your build however you see fit. We’ve compiled a list of some standout projects for your inspiration.

In addition to the builds we’ve featured here, some classic dry box projects include Modern Hobbyist’s simple box with silica beads, Becky Stern’s four-spool DIY dry box, Thomas Sanladerer’s spool-winding storage solution, and the Anybox designs from Anybot. Active drying is less common as a DIY project, but there’s Tinkerman’s modded food dehydrator and Kevin Lee’s unique bucket dryer as examples.

HANDY_BEAR’S IKEA SAMLA DRY BOX

This is the classic storage box conversion, with space for four spools that feed directly to your printer.

• Approximate cost: $70
• Complexity: Medium
• Number of spools: 4
• Where to find it: Instructables, YouTube

RICHARD HORNE’S HEATED DRY BOX

This project improves on the standard desiccant dry box by adding a heating element for active drying.

• Approximate cost: $60
• Complexity: High
• Number of spools: 2
• Where to find it: RichRap, YouTube

BREAKS’N’MAKES’ CONVERTED FOOD DEHYDRATOR

Rather than rigging up your own heater, this project allows you to print directly from a food dehydrator!

• Approximate cost: $65
• Complexity: Low
• Number of spools: 2
• Where to find it: YouTube

Commercial Options