Overview

I've designed a few filament drybox solutions in the past, but I've never been completely happy with those systems. For this brand new design I set out to create a drybox system that meets all of my requirements and fits perfectly into my workflow and setup. Does that mean it'll be perfect for you? You'll have to decide that for yourself, but here are the features that I found important to include in this design:

• Humidity control for the lifetime of a spool. Every new spool gets dried first in a separate filament dryer, then sealed into one of these dryboxes. It stays in the drybox until used up, and the humidity level inside the droybox remains good for that entire time.

• Center axle with passive rewinder. The system includes a spring-based rewinder that fits inside the filament spool. This design suspends the spool inside the container so that it remains centered and won't contact the container walls, even if the container is tipped sideways or turned upside down. It works with both plastic and cardboard spools, even damaged cardboard spools with bent edges. The rewinder adds minimal drag on the filament while still allowing a significant length of filament to be retracted into the container without tangling.

• Rechargeable, spill-proof desiccant container. This design includes a two part desiccant bin that snaps together permanently so desiccant will never spill out. The desiccant bin snaps into the lid of the container and can be easily removed to place into an oven or dryer when the desiccant needs recharging. The desiccant bin is sized perfectly to fit into a drying system based on Polymaker's PolyDryer that I was already using.

• Filament database management with NFC tags. The system includes filament tag holders designed to fit my favorite printable filament swatches. The tag holders allow for an NFC tag to be placed inside them during printing. I use that NFC tag to store a URL identifying the spool inside each drybox, and when loading filament into one of my printers I can scan the drybox tag and then a separate tag on the printer to assign spools to printers and automatically keep track of filament usage.

• Simple construction with minimal extra hardware and tools required. This design doesn't require any holes to be drilled in the container and doesn't use any bolts or screws. The rewinder needs four bearings and a spring from a badge reel. The lid uses a silicone foam strip to create its airtight seal. Everything presses or snap fits into place, making assembly as quick and simple as possible.

Printing the Parts

All of the included STLs are designed to print in the orientations that they'll load into your slicer without needing supports. I recommend printing the parts for the container itself (lid, left and right supports, and tag holder) using PETG, which will help them to be a bit more sturdy so they can stand up to repeated use over the lifetime of the drybox. The desiccant bin's two parts should be printed with a material that can withstand the heat of whatever setup you're using to recharge your desiccant. I'm using ASA for mine. I've also been using ASA for all the rewinder parts, but PETG should be fine for those if you prefer. Finally, there are two small parts that fit into the filament opening (inlet and plug) that should be printed with TPU. I've been using 95A TPU for those, but softer TPU filaments should be fine as well.

As far as print settings, I'm using a 0.4mm nozzle and 0.2mm layer height for everything. All other slicer settings are pretty standard... 2 walls, 5 top layers, 4 bottom layers, 15% gyroid infill. If you're printing some of your parts in ABS or ASA, the STLs are not pre-scaled to account for filament shrinkage, so make sure your filament profile is tuned to account for shrinkage so that everything will fit correctly.

Required Hardware and Tools

In addition to the printed parts, each drybox requires one cereal container, 4 bearings, the spring from a badge reel, a length of silicone foam cord, some desiccant, a hygrometer, and an optional NFC tag. I'll include Amazon links below to the exact items I'm using, but I'd recommend shopping around since Amazon's prices on these items fluctuate a lot. Also, in the interest of full disclosure, the links below are Amazon affiliate links. The small amount of income that I get from those links does help to support my work on this and other projects, so thanks for supporting me in that way. If you'd prefer not to use the affiliate links, I'll include non-affiliate links in parentheses.

• Cereal containers: You're looking for 4L containers branded as Praki, Wildone, or Skroam.

  • Skroam: https://amzn.to/3ZITLVK (https://www.amazon.com/dp/B0FJY5V1VF)

  • Praki: https://amzn.to/4qGQC3C (https://www.amazon.com/dp/B08TWH2QHV)

  • Wildone: https://amzn.to/4tNeIg0 (https://www.amazon.com/dp/B07NP98YKY)

• Bearings: I recommend the open, ungreased ones that are designed for use in fidget spinners. https://amzn.to/3OfbVfn (https://www.amazon.com/dp/B0F1TGX3PR)

• Badge reels: You'll be disassembling these to harvest the spring inside. https://amzn.to/3Oly5wq (https://www.amazon.com/dp/B0BD1W4X3C)

• Silicone foam cord: Any length is fine depending on how many containers you're planning to build. The important dimension is the 3mm diameter. https://amzn.to/4aJ2Uml (https://www.amazon.com/dp/B0CW9DVZXY)

• Desiccant: I've switched from the color changing silica gel beads to activated alumina desiccant, but either will work just fine.

  • Activated alumina: https://amzn.to/4kLujZk (https://www.amazon.com/dp/B0B81VM24F)

  • Silica gel: https://amzn.to/4cBDMAh (https://www.amazon.com/dp/B01I5Y2DG6)

• Hygrometers: Any hygrometer with the commonly used rectangular form factor should fit, but after extensive testing I've found that these ones tend to be more accurate than others I've used. https://amzn.to/4tXLv22 (https://www.amazon.com/dp/B09TY4CS35)

• NFC tags: Any of the 25mm round NFC tags should fit. These are the ones I've been using. https://amzn.to/4rRUtfe (https://www.amazon.com/dp/B087M9FLM4)

When it comes time for assembly, these are the tools I recommend:

• Needle nose pliers - for bending the badge reel spring and inserting it into the rewinder.

• Scissors or hobby knife - for cutting the foam cord to length.

• Tweezers - for inserting the foam cord into the lid.

• Hot glue gun - for attaching the tag holder to the container.

Assembly Guides

Container

Rewinder

Spool Adapters

Desiccant Bin

Spool Adapters

I'll post links here to spool adapters that have been tested and verified by the community. If you're looking for an adapter to fit a specific brand of spool, check the lists below to see if someone has made one. If you want to contribute a new spool adapter, post it as a remix of this model, include the filament brand and the spool dimensions that you entered into the OpenSCAD file when you created it, and after it's been verified I'll add it here.

Cardboard Spools

• 3DHOJOR - https://www.printables.com/model/1624918-3dhojor-spool-adapter-for-filament-storage-2026

• Elegoo - https://www.printables.com/model/1615869-spool-adaptor-for-elegoo-spools

• Inland - https://www.printables.com/model/1615869-spool-adaptor-for-elegoo-spools

• Overture - https://www.printables.com/model/1617553-polymaker-and-overture-spool-adapter-for-filament

• Polymaker - https://www.printables.com/model/1617553-polymaker-and-overture-spool-adapter-for-filament

Plastic Spools

• Elegoo - https://www.printables.com/model/1622271-elegoo-older-plastic-spool-adapter-for-filament-st

• Kingroon - https://www.printables.com/model/1637842-kingroon-holey-plastic-spool-adapter-for-filament

• Numakers - https://www.printables.com/model/1620495-numakers-spool-adapter-for-filament-storage-2026

• Voxel - https://www.printables.com/model/1632306-voxel-spool-adapter-for-filament-storage-2026

Extras

To complete my filament storage setup, I use the following additional items:

• Filament swatch: https://www.printables.com/model/905429-favorite-filament-sample-customize-color-swatch

• PolyDryer adapter for recharging desiccant: https://makerworld.com/en/models/886565-desiccant-dryer-and-cover-for-polymaker-polydryer

• Spoolman and FilaBridge: I host instances of Spoolman (https://github.com/Donkie/Spoolman) and FilaBridge (https://github.com/needo37/filabridge) on my local network to keep track of filaments loaded into my printers and how much filament is left on each spool.

  • NOTE: The original author of FilaBridge has stopped updating the project. Here are links to two different forks of the project that I have used and can recommend:

  • https://github.com/sargonas/filabridge

  • https://github.com/ThetaSigmaLabs/the-moment