Summary

This is a customizable rose pattern also known as a rhodonea curve.
See http://en.wikipedia.org/wiki/Rose_%28mathematics%29

Instructions

WARNING: It seems that the STL cannot be generated for some reason. I have rewritten this into a working script. Please use this instead : http://www.thingiverse.com/thing:50249

This script will generate an artistic rendering of a Rhodonea curve (Rose). You can set the N and D values to affect the look of the curve (see http://en.wikipedia.org/wiki/File:Rose-rhodonea-curve-7x9-chart-improved.svg).
You can either use a sphere, a cube or a cylinder to draw the points of the curve (I prefer sphere), and define how many points you want to be used to draw the result. You can also control the size of the pencil and the thickness of the curve. The rose radius will set the radius of the petals. This will basically mean that the rose should fit in a circle with that radius.

It is highly suggested not to enable the "high detail" option as it will take a very long time to generate the preview. I would suggest to use 100 points if you enable it. It does give better results, if you are ready to wait for it to finish rendering.

The 3D effect allows you to control how the shape will look in 3D space. None means it will be a flat surface showing the rose, the sinus, cosinus and sinus+cosinus will use different algorithms to move the rose through 3D space into a weird shape. The rose will still be visible the same way if looked at directly from the top. The "rose" 3d effect will use the same algorithm to generate the rose as to determine the position of the point on the Z axis. This has the effect of generating a sort of looping of the petals of the rose.
Experiment and enjoy!

Customizable Rose pattern