Printing with colorFabb XT-CF20 - UM2 in Help, Tips & Tricks Posted September 3 There are many other filaments that have carbon fiber in them and some glass fiber ones. I find the best are Nylon based ones. Easier to print with really strong layer adhesion. You just need to store it in a dry container and dry it before use. XT-CF20 doesn't really have good layer adhesion but I normally print at 30mm/s to help make it stronger. Most filled filaments give a really nice finish and the colorfabb nGen lux looks really good, hiding the layer lines if you dont mind paying for it.