Tutorial - Making iPhone 4s in SolidWorks Part 3?

Here is third part.
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Step 1:
Top face >> Sketch.
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Step 2:
Draw two circles.
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Step 3:
Extrude cut by 15mm.
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Step 4:
Chamfer the edges by 0.275mm at 45º.
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Step 5:
Top face >> Sketch.
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Step 6:
Offset the circular edge by 0.13mm and 0.26mm.
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Step 7:
Split line and select the face. Click OK.
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Step 8:
Back face >> Sketch.
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Step 9:
Draw a circle and offset it.
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Step 10:
Split line and select the back face. Click OK.
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Step 11:
Select the previous sketch and then Extruded cut.
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Step 12:
Extrude cut by 0.25mm with inner contour.
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Step 13:
Inner surface >> Sketch.
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Step 14:
Draw a circle.
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Step 15:
Extrude cut by 1mm.
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Step 16:
Inner face >> Sketch.
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Step 17:
Draw a circle.
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Step 18:
Extrude cut by 0.50mm.
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Step 19:
Inner face Sketch.
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Step 20:
Offset the inner edge by 0.250mm.
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Step 21:
Split line and select the inner face. Click OK.
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Step 22:
Dome the internal surface by 0.5mm.
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Step 23:
Select this face >> Sketch.
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Step 24:
Select this edge and Convert entities.
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Step 25:
Extrude it up to this surface. Uncheck Merge result.
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Step 26:
Back face >> Sketch.
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Step 27:
Draw two concentric circles.
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Step 28:
Here is fourth part. http://grabcad.com/questions/tutorial-making-iphone-4s-in-solidworks-part-4