https://stationerymanor.com/products/kokuyo-mo-series-round-stencil-template-97018

Kokuyo has a circular stencil/template (WCN-CDTAS13), which one presumably holds down in the center and then uses the various slots with a pen/pencil to circle around to make their own custom chronodex stencil outlines.

It doesn't take a genius to see how Baum-kuchen could potentially use such a tool or stamp to make a branded chronodex that also might suggest the circular layers of an actual Baum-kuchen cake.

https://www.jptamerica.com/