An extension tube for 3D printer extruders, designed to make filament insertion smoother and more convenient.
A small tube that guides the filament, helping to prevent jams during manual filament changes.

It’s specifically engineered to fit 3D printers equipped with a 0.4 mm nozzle.
After printing, the tube may need to be slightly refined using a file or rasp.

I optimized this design for 0.4 mm nozzles—though it can also handle 0.3 mm nozzles when properly sliced—and once printed, the surface should be lightly sanded to ensure smooth filament feed and ejection.