Step 6 Applying an outer glow is achieved using a similar process to the previous stage, except it obviously occurs outside of the shape, using Outer Glow.
Personally, I like to use this tool sparingly as it allows you to accentuate certain features of an object, without looking like everything’s glowing. For example, here I want to give the impression that the pink elements in the droid are glowing.
To do this, select the shape, then choose Effects > Stylize > Outer Glow. As with the Inner Glow options, adjust the blending mode, blur and opacity. Leave the blending mode as Screen, as this is ideal for objects on darker backgrounds, with 100% opacity for maximum glow and a 2mm Blur. I used a light pink for the glow colour (#FF92BC).
Step 7 The next few steps are pivotal in creating the final effects. We’re going to create a custom brush that tapers, widens and then tapers again. This brush is going to be used for highlights and shadows.
Create a new layer. Select the Arc tool, which is on the Toolbar under the Line Segment tool. When selected, hold Shift while you drag the tool across to create an equally proportional arc.
Step 8 Select your newly created arc and rotate it 45 degrees clockwise (Object > Transform > Rotate -45 degrees), until it’s horizontal with the ends facing down. You should now be seeing half of your tapered brush stroke.
We need to mirror this line, in order to make a shape out of it. To do this, first right click and select Transform > Reset Bounding Box.