The 2D Shape Editor
Lets hit the ground running! (Anyone remember the motorway scene in Bevis and Butthead Do America?!) You can find the 2D editor by clicking 'Tools' from the menu, then selecting the 2D shape editor. A new window will open..

The 2D shape editor is easy to use once you've built something a couple of times in it. All the buttons on the left and middle are self explanatory (Hover your mouse over them for a tool-tip). The buttons on the right side are for building your 3D shape, and may appear alien to you at this point. all the buttons are repeated in the drop down menus, if you prefer that.

Navigation and preparation is also simple. Click and hold the right mouse button on the empty grid, and drag your mouse to move around the grid. To prepare, set the grid the same as the editor, using "Edit > Grid >". 8 or 16 is recommended.

Important Notes:
- Smaller grid scales might not be visible without zooming in very close (Which makes it more difficult to create your shape).
- If you ever get lost on the screen (Which you will), use the "View > Move Camera to Origin" option.
- You can save your 2D shapes separate from the map. Like maps, save them often!

Ready to Go
Now that we're ready to go, we need to create the outline (Cross-section) of our corridor. Decide on a shape for your corridor. It can be handy to use squared paper (Graph paper) to design your 2D shapes. Use the default square as a basis of your 2D shape.

To move the corners: Click and hold the left mouse button to select and drag the vertices (Corners) of your 2D shape.

To add more sides: Select one of your vertices. You'll notice that when you click on a vertice, one of the sides becomes bold. This is the side that will split in two, so make sure you've chosen the correct side. Then simply click on the following button:

The 'Split Side' button.

Use the grid lines to help you make the shape, making sure it is symmetrical. Try to ensure you build the corridor to your chosen scale, using the grid lines to help you. You can also zoom in or out to get a better view of your shape, using the zoom buttons:

The 'Zoom' buttons.

You should end up with a cross section of your corridor which looks something similar (or not) to this:

From 2D to 3D
Like Magic

Now it gets a little more complicated. The thicker, grey lines in the 2D editor are your axis. Whilst creating a curved corridor, the tightness of the curve will depend on it's position to the axis. To clarify, the editor will use these lines as a turning point for your curve. The closer to the vertical line your shape is, the tighter your curved corridor will be (Don't worry if this isn't clear to you yet).

So, to create a basic curve, we first need to move our shape to the correct position on the grid. To do this, using the left mouse button, and click and hold on the orange square in the middle of the shape, and drag it into the correct position. You will need to move it so that the left side of your shape is several squares to the right of your vertical normal, as shown;

The shape should be entirely on the right side, and not touching the vertical axis at any point. It is worth saving your shape at this point if you haven't done already.

To create your curved corridor brush, use the 'Revolved Shape' button, shown below. A small window will appear with some options.

The 'Revolved Shape' button.

This screen is self explanatory, but I'll still explain if required; the 'SidesPer360' is the number of sides your corridor will have per complete turn. The higher this number, the 'smoother' and more 'round' the corridor will be. The 'Sides' is the number of sides your corridor will make up of this complete circle. The axis is unimportant. For example, using the numbers in the image above, with 16 SidesPer360, 4 Sides will result in your corridor having a 90-degree quarter turn, as shown below.

At this point you may wish to experiment with your own values, and by moving your shape closer/further away from the vertical axis to see the effect. If you haven't got your layout down on paper, as you probably have now, a 45-degree turn (half of the image above) will provide you with a lot of freedom when playing around with your layout, as this will allow you to 'piece together' sections of your corridor using your top-down view, to create winding layouts, also shown below.

To create a straight corridor section, use the 'Extruded Shape' button shown below. The depth is simple the number of units long the brush will be. You can always stretch the brush afterwards. Easy huh? These new brushes can be cleverly mixed into the architecture of your level, and isn't restricted to just corridors.

The 'Extrude Shape' button.

Creating Curved Surfaced with Smooth Lighting
The problem with creating curved objects made from BSP, is that the lighting can often appear shoddy, as lines or different shades of light for each surface. You just can't get away with this in professional levels. This can be fixed easily by converting the BSP into a Static Mesh, within UnrealED.

Firstly, isolate your corridor from any other brushes or meshes that may be touching it, by moving it away into an empty space. If you have an additive curved brush, such as a curved pipe, place it in an empty open area of you level (not the void). If you have a subtractive curved brush (such as a corridor), place it in an empty solid area, such as the void (not open air).

Next, intersect your corridor (making it one complete brush), using the intersect tool. This is an important step. If you have a subtractive brush, remember that the the area outside your brush will become solid. Make sure this is kept to a minimum and ensure that players can still walk/see inside it.

The "Intersect" tool.

Finally, add the intersected brushes to an open air area of your world (not the void), and rebuild (F8). Before you convert the brush to a mesh, make sure you are happy with the result. The final step is to select the newly-created brush using one of your 2D views, open the Static Mesh browser (The green arch button), and import it into a mesh using the steps below..

1. Select the 'Create static mesh from selection' button. A new window will open..
2. input 'myLevel' as a package (This will embed the mesh into your map). Group is optional and is only used to organise your meshes. Name is what you want your new mesh to be called.
3. Select OK. You will now be able to use the mesh in your level. Select the 'myLevel' package to see it.

Your lighting should look much better on the mesh than it would on a curved brush.

Its far better to create complex meshes using a 3D modeling program such as Maya, as you'll be able to create detailed and optimised meshes. However, if you don't have the skills or have not yet learnt a 3D modeling program, making them in UnrealED is a basic option for you, although it does have a couple of quirks.