Models are printing with a scratch on the side I just recently got an Ender 3 and have been trying to learn the do’s and don’ts. My first model looked like it had under extrusion and stringing, but my second model looks like it has frequent “scratches” along the sides. I printed it with two materials, a white sample PLA that came with, and a black Sunlu PLA.



I could use some insight on how to improve it, I’m seeking to make some fairly smooth looking models similar to Fat Dragon games.
The vertical lines you are referring too are the result of ringing or vibration. This is commonly encountered with high print speeds, high acceleration values or if a sudden change in direction takes place.

This can be solved by printing slower, decreasing acceleration values and checking for mechanical issues. E.g. the belts may be too flexible (or contain a tension spring) or there may be a loose part somewhere.