This will show you howto make plastic shapes with inset lines
1. Create a new document, white background. Make an oval with the shapes tool.
2. Now, apply the following styles to it under Blending Options:
Inner Shadow:
Inner Glow:
Bevel and Emboss:
Stroke:
It should look like this
3. Now we want to customize our shape. Make an oval with the selection tool over that layer.
3a. Press Delete, do this to any other sides.
Starting the inset lines...
4. Make a new layer. Now make a selection similar to this and fill it with white (#FFFFFF):
4a. Go to Select>>Modify>>Contract, put 1px in. Hit delete.
4b. Fill that selection with a slightly darker gray. Repeat step 4a.
5. Now press Ctrl and click the previous layer, goto Select>>Inverse.
5a. Now click on the layer with the inset lines. Press Delete.
6. That's it! Just add some text, and rivets (with the eraser), and you have a nice plastic image.
More Tutorials: 
