YARN! I chose to use 7 different colors (I have a weird obsession with rainbows and colors), but I think this design would look really cute in all one color, or having all but one ring in one color and then the last ring in a contrasting color (like all white and one black).
Circular Needles Size 10.5 (you can use a different size, but my stitch and row count are based on this size)
Note: To get the best outcome, or at least more symmetrical, use all the same brand yarn. My red and yellow were different, but they weren't that different, so it was okay.