Sovol filament holder barrel with PTFE inserts

The inject molded filament holder barrel has somewhat too much friction to work properly. It makes annoying sounds and can sometimes be problematic for extruder to pull filament properly. Some people have added PTFE film to the holder but I don't have it and attaching it is a little problematic (and zip ties are ugly to keep it in place).

I made a change to Sovol's step file by adding slots for PTFE tube (the same that is commonly used as Bowden tube or to otherwise guide filament). 4mm tube is not optimal as it is quite thin, 6mm works better but is not very commonly used by 3d printers.

I also added brackets for SV06 and SV04 to keep the barrels in correct orientation as the slots for PTFE tubes are only on one side of the barrel. 

Print the suitable model for your printer, use supports at least for the part that locks with the ring. It may be a little tight, I used slip-joint / water pump pliers to grab the ring and twist it a couple of times in the printed barrel before attaching it to the metal bracket.

Add 1, 2 or 3 tubes depending on how much extra PTFE tube you have and what seems to work for you.