Step 3 What I’ve found crucial in helping define how to colour a shape is the creation of a light source. Setting this up is as simple as drawing a circle on the canvas to distinguish where the light is coming from.
A guide like this comes in handy when your illustration becomes more complex and confusing as you lose count of the shapes and gradients used.
Create this object on a separate layer and lock it.
Step 4 Let’s go back to the shape. Using the light source as a reference, begin colouring the droid. Start with the base as this helps define how the others are coloured.
Using the Gradient tool (G) with the Shape option selected, click and drag on the shape to define the gradation of the gradient. I’ve used the lightest gradient for the base and set it to ‘Radial’ in the Gradient palette (Window > Gradient).
Ensure that the lighter shade of the gradient corresponds to the position of the light source. In this case, the lighter colour in the gradient begins at the top as the light source is above the droid.
Step 5 The second step to adding depth to the shape is giving the base of the droid an inner glow. An inner glow is useful as, regardless of the angles of the gradient, it creates a shadow that follows the edge of the shape, giving it a beveled appearance.
With the base shape of the droid selected, chose Effects > Stylize > Inner Glow. Select the ‘Edge’ option, a shadow colour and a blur amount. If you’re using my droid and colour scheme, select #123860 as the colour with a Blur of 8mm.
Choose Multiply for the blending mode. Set the opacity to 70% for a rich, dark shadow. As shapes vary, so does the level of blur applied; the smaller the shape, the less the amount of blur.