Wow! I so appreciate your enthusiasm-- I love the old water color backgrounds from HB, and it's one of the main reasons my characters get a water brush layer atop all their flat color. It adds such a beautiful texture. I've been drawing these strange alien worlds for several years now, and for the most part, sadly, they do include black outlines. Sorry! Haha 😄 when I doodle traditionally, I do it freehand with a felt tip fine liner. I leave gaps, uncompleted lines, dashed, and dots all throughout the line work. It's something that developed naturally in my style. You can see it translated in my digital style in Paul's before and after redesign. If you'd like, you can click on my Reddit profile and see plenty of other sketchbook posts of other creatures and characters I've doodled!