Here are the initial thumb designs.  I spent about 15-25 minutes per each design.  I decided that these four were the strongest.

Out of these, I chose to refine and iterate # 3

My favorite part is refining and expanding on a design.  I enjoyed seeing this character evolve.

it only took a few hours to design these.

Here I added materials, textures and fixed any outlying design problems.  I added a turnaround to make this a good 3-D reference.