The other part: I used only Subsurface because the pencil is a cylinder-based model, so it doesnβt need another modifiers.
For example, the roughness map of the bottom metal was created like below image.
The gradient image was hand-painted in Blender. And the scratch image was mixed with it.
Both image was adjusted its bright and contrast with ColorRamp node.
@heydotory Thank you for taking the time to answer my questions you are an absolute star for putting so much effort into your reply. As a beginner I look up to your skill and admire your work, it means a lot when people like you willingly help out an ambitious beginner like me . Thank you