I created some mermaid illustrations for use on the new mermaid product line and some of its packaging. They had to be very simple with no gradients or complex line work so they could be manufactured in a number of different processes on materials like nylon and rubber.
A real challenge was how to draw a mermaid that seemed graceful and beautiful but not sexual. We didn't want the mermaid to look too old or too young and our goal was for her to look like a young teen (the products are for 2-6 year olds). Another designer and art director worked with me on the facial features until it was right for our audience.
Here are the two main illustrations, and an example of how one was used on a product with the tail extending off into a 3D element:

An umbrella using the illustration as the main element: