xshock tutorial_03 - Seamless Metal Texture

Create a new document with a size of your choice. Set the foreground/background colors to black and white (or simply press 'D'). Add a new layer and fill it with black.
Go the menu and click
'Filter -> Noise -> Add Noise...'

and set the values

'Amount' - 90 %
'Distribution' - Gaussian
'Monochromatic' - Checked
You should have something like this right now.
Now go to the menu again and click
'Filter -> Blur -> Motion Blur...'

and set

'Angle' - 0
'Distance' - 60 px
This is how it should look now.
To make the metal look more metallic, change the contrast using the menu
'Image -> Adjust -> Brightness/

'Contrast' - -55
Now, make a square selection which selects a nice part of your texture. I'm selecting a 190x190-square in this tutorial.
Go to the menu
'Image -> Crop'

Make sure to crop the square so that the unaffected (or 'uneffected') parts are cut off.
Alright. Select a major part (around two-thirds) of your square. The part must be the very left side of your square and must cover the entire height of your canvas. Duplicate the selection by pressing 'CTRL-J' and transform it using the menu
'Edit -> Transform -> Flip
Move the mirrored layer (which should still be selected) to the very right side of your canvas (use snapping). As you can see we will have to fix the hard edge of the mirrored layer.
We will do this by using a large softened eraser (with a size of about 100px). Erase the edge-
parts but don't touch the very right edge of the mirrored layer.
You should end up with a layer like this. With this mirror-layer, we're preserving the 'seamless' edge.
Finished. Reduce all layers to the background-layer and save the image for the web (or use it in Photoshop as a pattern).
I've set up an example page of what the finished metal texture could look like.

View example page