Add custom colouring tools such as Pencil,Line,Fill and Erase.I believe this would make creations look so much better and realistic!
The Fill would work just like the current color,but can be limited by Pencil and Line.For example,I want to make a camo,so I would make shapes with lines,but it would take me forever to fill them in with the pencil too,so I can just use the Fill or Bucket tool to fill the certain part of a fuselage/wing/etc. with the desired color!