My take, which is, roughly, 1) produce nicely aligned spots, and 2) stir.
With attached XCF.GZ, and the Curves setting I used to randomize the SolidNoise output (add at the end of your .gimp-2.8/tool-options/gimp-curves-tool.settings)
- create a 5x5 image with a 3x3 red circle on a black background, and copy to the clipboard
- create target image, fill layer with "clipboard' pattern, which shoukld give you regularly spaced red dots.
- create two layers; on each:
- Filters>Render>Clouds>Solid noise, and use a fairly small details size (X&Y sliders fully to the right). For the second layer, use a new seed to make it different from the first
- Randomize the result a bit (I use "Curves"' with a big sine curve (4 wavelenghts across the width)
- Filter>Blur>Pixelize and use the size of the red dot pattern
- Filters>Render>Clouds>Solid noise, and use a fairly small details size (X&Y sliders fully to the right). For the second layer, use a new seed to make it different from the first
- Filters>Map>Displace map on the "dots" layer, using the other two for X and Y displacement (2px for the pattern size I used)
With attached XCF.GZ, and the Curves setting I used to randomize the SolidNoise output (add at the end of your .gimp-2.8/tool-options/gimp-curves-tool.settings)