Thanks everybody, I appreciate the comments. I enjoy the pen and watercolor because it is relatively hassle free. I just throw some supplies into a backpack and since it's a light I can walk about anywhere with it and I can sit just about anywhere and still sketch as well though I usually take a stool or chair as well depending on how far I have to walk. I've got another one I did last Saturday I'll post soon, maybe tonight.
Derek, go for it, it's so simple you can do it anywhere any time and in my case at least passersby rarely take notice and if they do it's just a quick comment. When you set up a tripod and pochade box in a busy area you end up drawing crowd, and that can be rather intimidating, not so with the sketching.
Donna, it probably helps that I did architectural rendering quite a bit in high school, that and drafting were actually my hobby back then, I've understood perspective for a long time now even though I haven't really been pursuing fine art until the last couple years.
Aguiar, thanks. The only major issue with my drawing on the caboose is that I misjudged and ran out of paper. I tried to truncate it at first but it looks way wrong so I just settled for losing the very back part.
James, thanks these are 6 x 9.
Chantal, thanks. I've actually left quite a bit of detail out, I had 1 1/2 hours into it as is, I could easily have put 3 hours into if if I wanted to get real detailed.