I did one of these self portraits before but that was on a train, I haven’t really gone to do a long sketch on the bus but tried this one out today since the bus journey was rather long, around 30 minutes. I even got a fellow passenger to take me a picture.
I have used the mechanical 0.5 rotring HB visu-pencil for these sketches in my A6 Daler Rowney sketchbook.