I would like Autodesk Sketchbook to implement this "feature" on the Custom Brushes options. Just like we have the choice to create Standard, Syntethic, or Natural Blending brushes, this "Double Brush / Double Colour" would use the ColorWheel in RANDOM MODE.
By setting the Color Wheel Random's Parameters (on hue, X and Y posiions) and using a Custom Brush with many different Gray Values, you could implement this idea.
The different values in grey tones on the Custom Brush will equal the hue and value of the colour but choosen randomly amongst the Randomness rate set by the user.
