EIBOS 3D, the filament and filament dryer maker, just filed a US patent for its new dual-spool dryer, Polyphemus, that solves the problem of uneven spool drying. The new device sits spools on rollers and gently rotates them over the main heating unit — like perfectly roasting a marshmallow over a campfire — to avoid "spot deformation, melting, and other unwanted effects" when heat-drying filament, the company says.