For this example I’ll be creating the flower in the tutorial thumbnail. Make 2 lines with the pen tool, no fill, and any colors.

In the last frame I moved the 2 lines closer together and applied a different stroke color to each. The higher the contrast between the colors the better it will look, but don’t worry you can change this later, too. Now go to Blend Options. Use the Menu to get there: Object>Blend>Blend Options

Use these preferences, but they will change if you want to blend a bigger or smaller object. Select your two lines and click Alt-Control-B.

The result should be something like this, depending on the size and color.

If it looks nothing like this, try to select them again and make it. If it looks kind of like this, but the lines are incorrect, check the Blend Options again or try to rotate the object a little. (Illustrator sometimes creates stray lines because of small errors.) From here the possibilities are

You can use blending to create petals, leafs, abstract shapes, and beziers (remember that screensaver?).

Keywords: Adobe Illustrator, Blending, lines, stripes, effects, effect, flower, futuristic, wallpaper design.