Who gets to paint the decals on the side of aeroplanes such as the Memphis Belle and modern day equivalents?

Well they are not decals, but actual illustrations done by artists from all walks of life. Most the old WW2 nose art was done by talented aircrew members or friends.|||When I flew a specialized transport aircraft in Europe, we commemorated 40 years of service with the original Disney artwork. It was made into a laminated sticker that was applied to the nose and coated with clear poly paint. Check out the link below: