One of the points of writing with a nice, thick fountain pen is that you can vary the line width quite a bit while you are writing, by applying more pressure on

One of the points of writing with a nice, thick fountain pen is that you can vary the line width quite a bit while you are writing, by applying more pressure on the nib. This leads to more pleasant calligraphy than you can ever get with a rollerball. Random example: https://www.penparents.org/img/twsbi_with_flex_nib_twsbi.jpg https://www.penparents.org/img/twsbi_with_flex_nib_twsbi.jpg