Drybox Dehydrator

3D printing raw materials (filaments) are hygroscopic, meaning they absorb moisture from the air. For my pediatric walker project, I needed to print thermoplastic polyurethane (TPU) for the soft rubber feet and polyethylene terephthalate glycol (PETG) for the strong joints. Both materials, especially TPU, are far more sensitive to moisture than the most common polylactic acid (PLA) filaments.

When damp filament passes through the hot extruder, the trapped water instantly turns to steam. This rapid vaporization creates pressure, causing issues like oozing, inconsistent extrusion, and poor layer adhesion. The result is a print with a rough surface finish and compromised strength. ince I print in my garage where humidity is often above 60%, I needed a reliable way to dry my filament and keep it that way.

While commercial filament dryers exist, most can only handle one or two spools at a time. A standard food dehydrator is another popular option, but it’s cumbersome moving filaments from dryer to dry box and difficult to use one to dry a spool during a print. I also explored online designs for storage dry boxes, but none offered the swappable and adaptable system I needed.

My solution was to build a custom dehydrator. I disassembled a food dehydrator and repurposed its heater and fan, installing the mechanism into the lid of a large, airtight container. This created a high-capacity system that can dry filament while printing. By simply swapping the active lid for a standard one, the container also functions as a sealed dry box for storage.

My tests show this setup pulls 2 to 10 grams of water from a brand new 1kg spool, proving how much moisture filament can hold even straight from the factory packaging.