Start with a suitable image:
Place it in Carbide Create on the background layer:
With snap to grid enabled use the curve tool to draw a closed polyline:
Then go into node edit mode, and right-click on each node to make it smooth which adds off-curve nodes:
(note that it may be necessary to toggle each node twice)
Turn off snap to grid and drag the nodes into position, remembering the rules of Bézier curves (see: Let's draw an "ellipse" with new users — very basic tutorial on drawing with the curve tool — also see: Let's Make a B (for anyone) )
Ryan Anthony was kind enough to post a photo of the finished project:
https://www.facebook.com/photo.php?fbid=2287741817993842&set=p.2287741817993842&type=3&theater