Originally inspired by Veltman’s block. However, I didn’t want to have cut-off dotted patterns (fitted to the shape you apply the pattern to).
This version creates the CMYK dots themselves, so you can have overlapping circles (this block randomly chooses between a version where the circles partially overlap, or not overlap at all), and where the edges of the circles are smooth (i.e. the CMYK dots get smaller on the outsides).
It’s based on examples I found here and here. It will take a very long time to create! So it’s more something to use to create a dataviz that will eventually be turned into a poster.