Making the Base Texture:
First off I guess I should give you some background info on my experience with texture creation. I started making textures when I found a simple wall editor for Wolfenstein 3D. I think my first texture consisted of "I rule" written crudely on a brick texture (I was quite impressed to see this in Wolf3D =) After that I started making textures for web page backgrounds and then Doom textures. Since then I have created hundreds (maybe it's thousands now) of textures for games such as Quake, Quake2 and Half-Life. My most recent project is creating the textures for Star Wars Quake, which has well over 1000 textures now.

You should have a good working knowledge of Photoshop and Wally for this tutorial. I try to word this as simply as possible but some Photoshop experience is required.

Alright, lets jump right into this. First thing we are going to need is a 256x256 document in Photoshop. Once you're done that find a good dark grey for your foreground color and a rusty color for the background. Now select Filter/Render/Clouds. You should get something like this:

I find that a bit too smooth, there's not enough detail. So lets add some. Select Filters/Brush Strokes/Accented Edges and enter the following settings

edge width: 7
brightness: 50

Now select Filters/Noise/Add Noise and enter the following settings

Noise Amount: 32
Uniform Distribution
Monochrome

After that select Filters/blur/Gaussian Blur and enter the following settings

Radius: 1.3

Now you should have something similar to this:

Making the Details:
Now we have a nice generic texture. From this we can do a number of things. What we'll do is make a series of panels on the top and bottom and have some pipes in the middle. The trick here is to make the texture seamless.

First, I maximize the textures workspace. Next I duplicate the background just in case I screw up the original base texture, we'll be doing the panels on this duplicate layer. After this I draw a rectangular selection around the bottom (about 1/3) and holding shift I select the top quarter. What I'm left with is 2 rectangular selections excluding a middle bar (this is where we'll put the pipes later).

Now, hold down shift and press the left arrow key until the selection is about 3/4 off the texture. Still holding shift draw two more selections exactly like you did the first time from where the first two selections end to the edge of the texture.

Now hold shift and press the right arrow key until the selection doesn't appear to have any vertical edges (and press the right arrow key a few times more after that).

The reason we went through this is so that the bevel is without any vertical seams. With that being said let's go ahead and bevel. Heres what my texture looks like after the bevel.

Let's add some more color to these panels. Create a new layer and select one of the spots where the panels are. Now choose:

Gradient: Linear: Foreground to background.

Draw the gradient line vertically down the selection. Repeat this process for the second bevel. You don't have to worry about creating seams and expanding your selections as gradients are consistent.

Lastly we add a small drop shadow coming mainly from the top panel. It depends on where the shadow from your bevelled panel is.

The Pipes:
Create a new layer, call it pipes.

Now you need to create a new gradient. It should go from black to light grey and to black again. After this click on the light grey in the middle of your gradient and pull the little sliders (or dots as they look like in the gradient designer) out towards the black. The end result is a gradient with mostly grey in the middle and bits of black at the ends fading into it.

Make a new layer on top of the pipes and draw a selection that is as wide as the pipe but only one pixel thick and fill it with black. move the selection over three spaces and fill it again. Once you've done a few of these you can duplicate and merger layers to speed up the process. Keep doing this till your pipe has black lines running vertically down the whole length. You may also want to nudge the layer a bit once you're done to ensure even spacing.

After that, duplicate your layer of black lines and using curves or brightness / contrast make them white. position the white lines so they are each next to a black line. Next choose "Soft Light" From the layer blending modes drop down box.

While on the pipe layer (the first one with the gradient) choose: Select: Load Selection: Pipe Transparency. Go to the original generic texture layer with the selection still on and move it down into the middle of the bottom panel. Choose: Edit: Define Pattern. Move the selection back up over the pipe (hold shift and press the up key) Make a layer above the pipe gradient and fill with the pattern.

Last step. Merge your pipe layers into one layer. Load the selection of the pipe layer (Select:Load Selection: pipe transparency). Choose: Select:Modify:Expand and expand by one pixel. Now make a new layer underneath the pipes layer but on top of the generic texture layer. Fill that selection with white and change the layer blending mode to "Soft Light".

Well, that was relatively painless =) To finish up the texture I duplicated the pipe and it's soft light 'block' around it. I then moved them down a bit and applied variations on the the second pipe (a nice gold color). After that I applied a blur on the pipes so they fit in more with the background. And as a final step I used the rubber stamp to get rid of some seams (seams happen...)

Porting:
The final step is to make this texture useable in Half-Life. Download a copy of the newest Wally. Once it's set up go back into Photoshop, flatten your image and choose: Select all. Copy the texture onto the clipboard, go into Wally and paste. Remember to choose Half-Life as your game type.

Choose an appropriate palette, remip and save!

Conclusion:
I hope you learned something new from this tutorial. If you have any questions relating to this tutorial send them my way.