We start off with a blank white canvas, and we draw a selection with the Marquee Selection Tool. TIP: Hold SHIFT to create a perfect circe.
We can then paint or fill this any color we want, in a new layer:
Now goto the layer properties, and choose gradient overlay. We want to choose a radial gradient, from white to black (or you might want to choose your own color). You may also need to increase the scale of the gradient:
Once we have done this, we will create a new layer and draw a selection of a rectangle like so: (It doesn't have to be perfectly in the middle, as we will move it after).
Now we will fill this rectangle in (on the new layer), choose a dark gray color or one that matches your gradient:
You will notice that it does not line up with the screw head, so to fix this Ctrl-click the screw heade layer and align horizontally and vertically using the move tool. Then goto Select > Inverse and hit delete (make sure the rectangle layer is selected). We should have something like this:
Now Ctrl-click the screw-head again to make the selection and with the rectangle slot layer still active, goto Filter > Distort > Spherize. Choose Normal and 100%. We should end up with the following:
Next, we can go into the Layer Styles of the rectangle slot and add an Inner Shadow, choosing a size of 15 or so:
We're almost done. To add a little more to it, and make it less perfect-looking, we can goto Filter > Noise > Add Noise on both layers. To have this show up on the screw-head, we would need to change the gradient overlay to something like Hard Light, or reduce the opacity of the overlay. We would end up with something that looks like this:
You can then use Edit > Transform > Rotate, to rotate the screw-heads:
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