Right.

There's actually not a whole lot more to this tutorial. What happens next is that I add two additional layers: Equipment, and Furniture. Equipment is for the items that are theoretically built into the ship, such as computer panels, toilets, sinks, and similar. Furniture is for the stuff that can move around. You can make them one layer if you wish, but I find that this method helps keep things from accidentally merging when you're placing, say, computer chairs. It also allows you to make empty ships easily enough by simply hiding the furniture layer. You can figure out your own ways of representing these; typically, when I need a new thing, I search the 'net for an above view, shrink it to my scale, and trace over it. When that's done, I save it into a template file for later use.

When you're doing this step, you may wish that you set up your rooms differently. That's fine; go back and change them. In a lot of ways, the placing of the walls and the equipment is often intermingled for me; putting in items as you go helps establish and maintain a sense of scale to avoid things like ballroom-sized bathrooms or rooms that are too small.

It's at this point we want to mess with those slope lines we made. Select that layer (you DId make them its own layer, right?) and go to Filters -> Light and Shadow -> Drop Shadow. Select the color and make it white, then set the offsets to 0, and the blur radius to 5. Make it so. Duplicate the layer that's created, then merge the three layers together. Move this layer to the top of your image. This makes the slope lines stand out on top of any furniture, equipment, or walls you put underneath them.

After that is the text and the lines. The text is Agency FB Bold Condensed, at 15px size. Typically, I keep them in narrow columns, because I think it looks better. The lines are three pixels wide, done by hand using the paintbrush tool. Do these on a new layer entitled 'Text.' Before you actually merge the text into that layer, perform the white drop shadow trick on the layer; this lets the line be easily followed to where it's pointing, even through walls. the text should be the uppermost layer of the image.

The border is trial and error; find something you like, and run with it. That's pretty much it.