One problem that a lot of people seem to have when needing to 3D print an item on an FDM printer, is the fact that purchasing and storing multiple rolls of filament can be both expensive, and annoying.
(…weiter auf 3dprint.com)
The „Ultimate Filament Colorer“ for 3D Printers
The ‚Ultimate Filament Colorer‘ is designed using a single Sharpie marker that coats 3D printer filament before it enters the extruder.
(Quelle: Youtube / 3D Print Board)