Stringing in 3D printed supports from an STL file is almost always caused by printing parameter issues—like insufficient filament retraction or poor cooling—rather than the STL itself.
When the printer moves between support structures, melted filament oozes out because the extruder doesn’t retract enough to halt flow, or the filament cools too slowly. Common culprits include too little retraction, overly high print temperature, low cooling fan speed, or slow travel speed.
To fix this, start with simple adjustments: Increase retraction distance by 0.5–1mm or lower print temperature by 5–10°C. These changes often stop oozing and reduce stringing quickly.