So these are the worst procedural photos ever. I did the last bit really fast and didn’t want to stop. I might set up a camera next time and do a timelapse if I have the patience to do it in one sitting.
I sketch out the basic shape with a really watered down white. Then lay down some deeper base colours (you can see the purple) then I keep building it up with brighter, less diluted colours.
I use a dry brush after a few strokes to soften the edges. It also makes the cloud look more naturally random.
A few sprays of blue and some stars dotted around.
Not unhappy with it.