Brush pens provide much more variation in line width than a fineliner pen. Their nibs have a broad base that then tapers to some good level. Commonly the nib is made from a conical bit of felt, but you'll find pens that have a real brush suggestion product of person https://inkpendrawingtechniques69135.thelateblog.com/37222104/new-step-by-step-map-for-ink-pen-drawing-techniques