Hopefully you've already watched pt 1, because this video enhances the basic 'chop and warp' technique by modifying the selection. Quick mask mode, as shown in this video, can be a very efficient way to modify a selection! It is a very powerful tool, though many digital painters avoid it.
The goal of thumbnail sketching is to generate a large variety of design possibilities in a short amount of time. With this goal inmind, it's not 'cheating' to take a non-traditional approach. This video shows how to "built" your thumbnail sketches instead of simply drawing them. Using robots as subject matter, we'll first build a set of modular components, and then mix and match them to create a large variety of robot designs.
Sometimes the digital workflow will behave completely counter to the way you learned to draw with a pencil and paper. Though it might seem foreign and strange, I encourage you to embrace these new opportunities! In this video I'll show how to iterate through a set of thumbnails by chopping them up into pieces, mixing, matching, and contorting them. Though it's not much like traditional 'drawing', it's a lot of fun and can be a huge time-saver.