Peter Schat's' Toonklok ("Tone Clock")
After listening to a talk by Albert van de Schoot, I decided to make an interactive version of the Toonklok of Peter Schat.(Java script)

Peter Schat was a Dutch composer.
He had the idea of arranging the 12 tones in an octave in a dodecagon. It turns out that there are also exactly 12 ways of making a "triangle" of 3 notes.

Click on a dodecagon to hear the 3 tones:

Peter Schat  made 12 very nice leaded glass windows with this theme. they are now in the the royal conservatoire in the Hague. Albert van der Schoot had a set made a set in his self-designed pentagon inspired home.
Toon Klok
This web page does not discus the more advanced musical theories behind the tone clock. But there are other sites that do that:
A page by Peter Schat himself.
Ironically, it starts with this quote: "I hate composition theories, philosophies of new music, recipes of how to compose, prescriptions of style. They're mostly unreadable, unintelligible, boring, and always humorless - whilst their necessity remains a big question."
An article by Theo Hoogstins (in Dutch)