Brush pens present much more variation in line width than the usual fineliner pen. Their nibs have a wide base that then tapers into a high-quality issue. Commonly the nib is fabricated from a conical bit of felt, but there are pens which have a true brush suggestion manufactured https://tysonfmquz.full-design.com/the-basic-principles-of-how-to-draw-with-ink-pens-79206507