1. Get the gradient tool; switch it to difference, and radial gradient.
Go mad!

2. Change the levels so that it doesn't have so many shades, and quite a lot of either black or white.

3. Duplicate the layer, and go edit>transform>Flip vertically

4. Duplicate the layer, and go edit>transform>flip horizontally

5. Duplicate the top layer, again, and go edit>transform>flip vertically.

6. Set the top three layers blending modes to darken or lighten, or any other that looks alright.

7. Spice it up with some highly saturated colour. Ctrl+U, colourize choose the hue, and put the saturation on full.

8. You’re done!!!

The attatched picture MAY be different from the end result of the tutorial - for two reasons :- one, the attatched file is just a symmetrical pattern I found in my psd folder, and two, all of them will be different anyway! tell me if you have any problems, or anyway you have used to improve the outcome