After being asked to write a tutorial as to how I did the 3d cog..here it is. For full size images, just click the thumbnail.

Open up a new image of any size you want, but for the purposes of this tutorial I’m making it 500×500. Ensure it has a transparent background. Resolution doesn’t really matter if you’re practising, but for printing you want around 300.

Then we’re going to draw some rectangles. Bear in mind that you can draw whatever you want. Long rectangles at the top will give a complete inner circle, rectangles at the bottom will give outer circles. Vertical rectangles create the “wedges”.

Next we’re going to apply a filter: Filter > Distort > Polar Coordinates. Leave it with Rectangular to Polar selected as default, and press ok.

Now, we’re going to change the perspective a bit, so that it looks a bit more 3d: Edit > Transform > Perspective. Click the upper-left box, and drag it to the right so that the image slants backwards, I dragged the box until the horizontal change was 10:

Doesn’t look very 3d does it? We’re going to change that. Right click the base layer, and select blending options. We’re going to add a drop shadow, and then a radial gradient:

Now we need to make it look a bit more 3d. Before you follow this step, if you want to change your original shape go back and repeat what we did earlier, saving the .psd at this stage will also help in future.

Select the base layer. Holding ctrl+alt, tap the up arrow until your image fills out – I did so fifteen times:

Now, select the very top layer and play about with its blending options:

Finally, select the base layer, and add a drop shadow to this:

And thats pretty much it. As you can see from my final image this time it didn’t turn out amazingly well, I think it’s better to use higher contrasting colours to begin with. Play about with the colours, play about with the rectangles and you’ll get varying results.