Pick a colour - any colour. Actually just leave it to the Scribble pen.
How's this for an idea. A pen that scans the colour you want to match then converts it to a HEX matched ink - or the digital stylus version can be used with a tablet or other touch screen device with a drawing programme.
The pen is an accurate color picker pen that picks any color around you and draws in that same color, the Scribble. It is being funded with a Kickstarter campaign which has yet to launch.Who is it for? According to the firm making the device: "… the color blind, kids, interior decorators, homeowners, teachers, artists, photographers, designers and students, the Scribblecolor pickerpen will make copying an exact color, any color from any object, an absolute breeze.”
It is kind of cool, if a little bit pricey at $US150 for the ink version and $80 for the stylus.