Made these expanding circle columns in Processing by rendering three circles without clearing the screen, and using hue shifting to keep it interesting. The colours go from dark and saturated, to bright and desaturated.

Circle

Spikey Hexagon

A variant which starts large and gets smaller over time, which creates the spikey ends.

Mixed shapes

Like the first version but with a mixture of three shapes: circle, hexagon and star.

Conclusion

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