Add a circular window to a rectangular surface

[captainj2410]

I've been asked by a few people to explain how to put a circular window into a rectangular surface on starships, so here it goes.
Step 1
http://i11.photobucket.com/albums/a153/captainj2410/Tutorial/1.jpg
Create a line which will become the hull of the ship when rotated 360 degrees

[captainj2410]

The hull should look something like this from the bottom:
http://i11.photobucket.com/albums/a153/captainj2410/Tutorial/2.jpg

[captainj2410]

Step 3
Bevel the surfaces (you could extrude them individually for more complex hulls, but this is quicker)
http://i11.photobucket.com/albums/a153/captainj2410/Tutorial/3.jpg

[captainj2410]

Step 4
Create a cylinder with no caps and change it's dimensions (usually Z axis) so it is just a 2d circle
http://i11.photobucket.com/albums/a153/captainj2410/Tutorial/4.jpg

[captainj2410]

Step 5
Use the rotate tool to rotate the circle so that it's slope matches the slope of the hull plates
http://i11.photobucket.com/albums/a153/captainj2410/Tutorial/5.jpg

[captainj2410]

Step 6
Move the circle so that it is on top of one of the plates. Select the plate and delete it
http://i11.photobucket.com/albums/a153/captainj2410/Tutorial/6.jpg

[captainj2410]

Step 7
Merge the two objects. Using the vertices of the circle and the previously deleted plate, create surfaces filling in the empty space around the circle.
http://i11.photobucket.com/albums/a153/captainj2410/Tutorial/7.jpg

[captainj2410]

Step 8
Once that is completed, select the vertices of the circle and create a surface
http://i11.photobucket.com/albums/a153/captainj2410/Tutorial/8.jpg

[captainj2410]

Step 9
Select the surface and bevel it with the Out property set to a negative number
http://i11.photobucket.com/albums/a153/captainj2410/Tutorial/9.jpg
It should look like this.

Now lather, rinse, repeat.