Prusa USS Drybox

Prusa USS Drybox

Why use the Prusa USS Drybox?

Wet filament = ruined prints

When wet filament hits the hot nozzle, the water inside instantly boils, expanding in volume. This creates steam bubbles that pop out of the nozzle, leading to stringing, oozing, and rough finish instead of smooth walls.

Left: wet filament after being stored in the open, Right: Filament stored and being printed directly from a drybox.

Never deal with wet filament again.

Most filament storage boxes are just repurposed food containers. We built the Prusa USS Drybox from the ground up for 3D printing, made from special hydrophobic materials. It's a sealed storage container built around a simple idea: place your spool inside, print directly from the box, and leave it there until it’s empty.

Unique quick access port

Access and load your filament without opening the lid. The sealed port keeps moisture out while you print, and it fits a PTFE tube perfectly for direct connection.

Universal Mounting

A clever central opening allows the box to mount directly onto your existing spool holder (the Prusa bayonet spoolholder). This way, we also minimized the free internal space where humid air could accumulate.

Stackable Design

The flat sides make the boxes fully stackable for neat organization. One box per spool: place it inside once, and leave it there until the roll is empty.

Fits the vast majority of spools

We made the box big enough to fit standard spools from just about any brand (up to 1kg), along with smaller specialty rolls.

Key benchmarks

Why you should choose the Prusa USS Drybox

• 95% less moisture absorption
• vs. ambient air
• 5× more airtight
• vs. generic dryboxes, on par with Museum-Grade Sealing
• 50% better sealing
• vs. generic dryboxes
• Stable for weeks
• 10% Relative humidity when using 50g silica gel

Moisture Absorption Over Time

Meassured with Prusament PCCF filament, without any silica gel in the box.

Why it matters? PCCF filament absorbs moisture rapidly. At 0.12% water content, printing quality degrades.

Museum‑Grade Sealing

Beyond measuring just the moisture absorption over time, we put our seal to the ultimate test using the CO2 Decay method. By measuring how slowly a tracer gas escapes the container, we can determine exactly how often the air inside is replaced by humid air from your room. While a basic zip-lock bag leaks air rapidly and even dedicated generic dryboxes struggle to maintain a total seal, the Prusa USS Drybox stays significantly tighter. Its performance reaches a level of airtightness typically only required for museum display cases used to preserve fragile historical artifacts. This means your filament stays in a controlled environment, shielded from the outside world, for much longer than standard storage solutions.