The diameter stability of 3D printing filament directly affects extrusion flow, printing accuracy, and print quality. Oversized filament may cause nozzle clogging, while undersized filament can lead to under-extrusion. Local lumps, neckdowns, and ovality may also result in uneven layer thickness. DALA Metrology provides non-contact in-line measurement solutions for PLA, ABS, PETG, TPU, and other filaments, with continuous monitoring of diameter, multi-directional dimensions, and local lumps, while recording production data for quality control.