This was my digital Spirograph  and the video that i made. The backgrounds were all done using squares and putting a filled color or a gradient color. The  Gradient colors that made you can see them on the swatches panel to the right all the way on top. If you want to make this you need to make a squiggly line with no fill color with a brush tool only storke. i made it in 1 stroke you can put it higher if you want. After you made your squiggly line use the V key and have the line slected. Then hit the R-key click right bellow ypur squiggly line not touching it but pretty close to it. There is going to this little red dot. You want to hold down Alt key in windows/Options mac while your object is still selected and pull slightly to the right and use Ctrl +D on windows and on mac Command+D hold it down, you should get a shape like it.