Free for anyone to use.

Tips:
. when using the lighten/darken/softAir brushes, set the opacity bar low, then repeatedly tap and stroke around the area that you want to shade/lighten. I usually keep them around 10-20%.
. shade wraps around the whole ball, but is more pronounced at the opposite end from the light source.
. Practice makes perfect. retry as often as you'd like. #remix

thanks! @The_adjudicator