Create a new file, I used 350x350 but you can use any size you want, make you image transparent, reset your colors by pressing 'D'.

Go to Filter>Render>Clouds, press Ctrl+F twice, the go to Filter>Sketch>Chrome (settings, Detail:6 Smoothness:5)



Filter>Artistic>Plastic Wrap

Settings:
Highlight Strenght:20
Details: 5
Smoothness: 14

Filter>Brush Strokes> Spatter

Settings:
Spray: 25
Smoothness: 10

Filter>Render>Difference Clouds

Press Ctrl + U, click colorize box

Hue: 43
Saturation: 68
Lightness: -17

Result:



This can be used as the background of a signature