I was cleaning out my sketch bag when I found a pen in one of the pockets… totally forgotten. I also forgot how much I enjoyed working with it for fast sketching. It’s Speedball’s felt-tipped calligraphy pen, the Elegant Writer.
I don’t know if you can purchase them separately but I bought a set of four at my local art supply store. There are two 2.0mm Fine pens, one 2.5mm Medium pen and one 3.0mm Bold pen.
The black ink bleeds into gorgeous pink, blue and purple when hit with water.