Filament Spool Clip for 3 mm and 1.75 mm

thingiverse

This filament clip attaches to your spool's side, holding the filament against its wall. It was designed for seamless use, even with poor printers, without post-processing or threading requirements. Simply grab 3 mm filament ends and press the clip onto the spool, ensuring the nob catches the ridge. Note that this clip may not suit all spool types. I've also created a 1.75 mm version, though untested due to lack of filament. An improved version is available at http://www.thingiverse.com/thing:49309 for better fit with well-calibrated printers.