Was pretty easy to do, got a nice base from a texture cd (think it was a wall photograph).
Got the contrast evenly spread out by clonestamping.
Added a light noise layer as overlay with a low opacity.
Added a little bit of color (light brown) againi on overlay with a low opacity.
Painted the (straight)lines in, made a selection on the original photo, inverted that selection and deleted parts of the lines with that.
Got drunk, but only HALFWAY!
Liquified it to make the lines whobbly.
Painted some cracks on the sides on an overlay layer.
In the meantime, i was constantly checking in max if the tiling went right.
I'll upload the psd later tonight...