Filament Storage on the Cheap

The piles of filament have started getting a bit silly, and even though I have a filament dryer, it would be nice if I could grab a spool and print right away¹. Plenty of people sell dedicated filament dry boxes, but the price would quickly add up for the couple of dozen rolls I already have in stock.

My constraints were:

Cheap
Airtight
Fits on a shelf

The Boxes

After a recommendation from a colleague, I picked up a set of six KICHLY cereal containers. They’re BPA-free² and airtight, and each box fits one full roll of filament. The price was right, so it was worth a punt.

A hand holding a clear plastic cereal container with a clip-down lid. Inside is a spool of pink filament standing on its edge, with a translucent printed desiccant holder in the bottom corner. — One roll per box, with the desiccant holder tucked in the corner

Keeping Them Dry

An airtight box only stops dampness moving in and out. If you put damp filament away, or open the box somewhere damp, the filament will still get wet, so you need something in there soaking it up. I went with Fonday silica gel beads, a 2lb tub of moisture-indicating beads that go from orange to green when they’re full. That means you can see at a glance when a box needs attention, and budget extra time for drying if needed.

A hand holding a translucent plastic jug of orange silica gel beads, labelled Fonday CoCl2 Free Desiccant, Orange Indicating, 2 LBs.

The beads are rechargeable, so once they’ve turned green they just need heating up to drive the moisture out. I’ve not had to do this yet, and previously with silica gel bags I’ve tried to microwave them with limited luck, so I think I will try just drying these in the oven when it comes to it.

The Desiccant Holder

The old silica gel sachets only held small amounts, so really I wanted a container to keep the loose beads in inside the cereal boxes. I have a 3D printer, so why not see if I can print something that fits the boxes nicely³?

A bit of googling later I found and printed a Corner Desiccant Holder for Dry (Cereal) Box by Xero. It’s a curved holder that sits in the corner of the box, out of the spool’s way, with a screw-on cap so you can tip the beads out to dry them.

This was printed on my trusty Bambu A1 Mini⁴, and each one takes a bit over 2h to print. If you are printing these yourself, note that printing them on the “side” with the cap facing the horizon led to better results than printing them on the base with cap facing the sky⁵.

I printed them in “clear” filament in the hope of seeing the beads change colour through the walls. It wasn’t super effective, as the printed walls come out more frosted than see-through, but at least it doesn’t hurt.

An empty 3D printed desiccant holder in frosted translucent filament on a wooden table. Its curved front is a grid of slots, with a ridged screw-on cap at one end. — Fresh off the printer, before any beads went in

Final Thoughts

I’m still in the process of printing the desiccant holders, and I need a few more of the boxes, so only time will tell if this works well.

Filament soaks up moisture from the air, and wet filament prints badly. I’ve def noticed the PETG starting to string a bit more as the weather has changed. ↩︎
Not that that’s a massive issue for my use case… ↩︎
Friends did suggest jam jars with holes in the lids, which would have been cheaper still. ↩︎
The same printer has churned out a split flap display, a case for the emailkb and the Beg Button’s walk/stop light mount. ↩︎
Mostly due to the supports needed. It takes a little bit of work to clean up the threads where the supports reach them, but the internal supports then come out via the cap and only need handling on one side. ↩︎