Developing Quilting Designs

I showed this picture of Cactus spines the other day, wondering what design I might come up with. I have been playing around with this idea.

Straight lines, no marking.

Not so straight lines, no marking.

I like the not so straight lines from above even better here, I used the 'triple' stitch on my machine. More thread for more definition. (The triple stitch is also called the stretch or lingerie stitch).