A spirograph-type curve such as would be obtained by rolling around the outside of an ellipse (major and minor axes of 2 and 1 respectively) a circle with radius 0.185 for three revolutions, the drawing point being 2.22 from the circle's centre.
This is a completely free image Roulette curve 18 that you can download, post, and use for any purpose.
Image License: CC0 No Rights Reserved
You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission, and at no cost. This image is completely free.