I've always created dummies in pencil, (digital notwithstanding), because dummies are just sketched ideas. Since the story and art will probably be changed, any effort more than a loose sketch is probably not the best use of my time. I might have a couple of finished color images from the dummy, but they would be included separately. All this makes perfect sense.
But I also know how hard it is to sell a picture book. I might have a great art with brilliant writing, (kidding), but I still need to show it in the best possible way. Pencil sketches may be fine, but using the same amount of time, are they my best sketching tool?
Before finalizing your dummy for an editor/art director it's possible to analyze the art and story to decide what drawing tool would best work for the sketches.
If you are not doing backgrounds — just focusing on an animal or child for the dummy — you might consider using a brush pen. That's because in one stroke, the line can vary from thin to wide. This can make a simple image pop.
I love my Pentel Arts Pocket Brush pen. Look at the fine point and the fat top! It takes an ink cartridge just like a fountain pen.
I haven't had the courage to try this for an entire dummy, but I've seen dummies created with Prismacolor's Col-Erase — erasable colored pencils. The dummies were created using a single color. It may be subjective whether the editor/art director thinks using color to create a dummy is appropriate, but the dummies created in color that I saw, have stayed in my mind for their unique look.
Another interesting drawing tool I've seen used is a wide graphic pencil. This seems to work well with dummies that have a lot of trees and grasses, or rows of buildings. This seems to soften a busy landscape.
Children's book illustrators are expanding artistic possibilities in every step of the book creation process. However book dummies are not often shared publicly because author/illustrators don't want to present an idea before it's time.
But the look of a book dummy is evolving. Now artists are creating more original dummies while working within the 'just-sketches-please' parameters. If using a certain drawing tool to make your dummy doesn't take any longer than using a #2 pencil, why not create with panache?
Twitter: @patriciakeelerInstagram: @patriciakeelerbooks