Making a blend is super quick:
- Draw two wavy lines with the pen or pencil tool to do this. Double-click to bring up the settings for these and set the smoothing up high for smooth curves).
- Select both sets of lines then go to Options>Blend. Select Colours or Steps. I selected Steps and entered 7 but the number of copies to make is up to you.
- Then go to Options>Blend>Make to see the effect.
- Play with different effects, eg, select the blend and go to Object>Expand and apply a gradient.
Sometimes the ends look straggly – select the Direct Selection tool and grab the end point anchors, align them so they centre horizontally and vertically and taper them. You can also pinch in other sections of the blend if you want to tweak the design.
You can create separate blends and join them together by going to Object>Expand then selecting each pair of end points in turn and using Anchor>Connect to join them. This enables you to apply a single gradient over the whole graphic. Not for the faint hearted if your blend is made from a large number of steps, though.