Link to featured cymatics video: https://www.youtube.com/watch?v=KU84ckD1AcA
How to draw the Heptagaon (7 sided polygon) and Heptagram (7 pointed star) with compass and straight edge. This method by Albrecht Durer, although not perfect it is a very close approximation.
From the Seed of Life and the foundation constructions of Scred Geometry it is possible to create close to accurate 7- heptagon, 9-enneagon and 11 hendecagon
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https://www.youtube.com/watch?v=VIpt-vAAyMQ