Step 3 Create another new layer at the top of the stack. Change the opacity of the Ellipse tool to 20% and do some more shading, using smaller circles to make it a little bit more detailed. Our model is now starting to take shape.

For best results, repeat this step a few times, making the shading progressively more detailed each time.

Step 4 Make a new layer and repeat step 3, paying even more attention to detail, using smaller circles. It doesn’t matter if you forget bits; you can always redo them. In the end you just have to make sure everything is equally shaded. Don’t overdo things though, because we will be doing more in subsequent steps.

Step 5 Here I noticed that my background colour didn’t really fit, so I decided to change it to something lighter and more colourful.

Pick a light colour for the highlights and a dark colour for the shadows. Until now we’ve worked in black-and-white; I picked a light yellow and a dark blue respectively. Create a succession of small circles to create the detail. Change this layer’s blending mode to Overlay and the opacity to 90%.