Tools of the trade -> Biro’s, yes basic pens I’ve got used to for making sketches of my digital work. It helps me think about whats going in the image and how it all works together.
I go through a lot of pens. Usually their lost before the inks runs out but I seem to be gathering a collection of empty ones. The current one has a broken top and its cool because it reminds me of school and having an irreverent attitude when sketching with them.