I begin with an image that has colors I like, usually two dominant colors that coordinate well. I crop the image to a square proportion.
I apply a Photoshop filter called Pixelate (mezzotint), then I apply a radial blur filter.
Next, I use the Distort-Twirl filter to create my main building block.
After duplicating this layer so that I have four copies, I flip or rotate three of the layers, so that I can place them into four corners, and the edges mirror each other.
I merge the layers into one, then duplicate the image. I rotate the duplicate by ninety degrees, then select a blending mode (usually either “darken” or “lighten” works best). This gives a four-point mandala.
Once again, I merge the layers, create a duplicate, then rotate the duplicate by 45 degrees. One final blend, and I have my mandala image, in this case, an eight-point mandala.
Here’s a video that goes through the steps.