Troughout his carrier Illum made many of his designs as water-colour paintings as exemplified below 

Illum Wikkelso Design Watercolor
Illum Wikkelso Design Watercolor
Illum Wikkelso Design Watercolor
Illum Wikkelso Design Watercolor
Illum Wikkelso Design Watercolor
Illum Wikkelso Design Watercolor
Illum Wikkelso Design Watercolor
Illum Wikkelso Design Watercolor