1 Create a 400*400 document.
2 Take the "Gradient Tool", set "Mode" to "Difference".
3 Play around with the tool.
4 Filter> Sketch> Halftone Pattern. (Size: 1 Contrast: 5)
5 Press Ctrl + U to get up Hue/Saturation. Check "Colorrize". Take a nice looking color.
And you're done.
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