There are some workarounds to this problem, but not many of them are as smooth an effortless as this one which uses erasable pen ink to add colors to the filament on the fly. Erasable pen ink is a ...

Best pens, according to experts | How we chose Fine ... Pilot Frixion ColorSticks Erasable Gel Ink Pens Frixion ColorSticks Erasable Gel Ink Pens (Set of 10) This colorful bunch is a go-to for ...