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://erinflotodesigns.com/collections/metal-stencils/products/bullet-journal-monthly-circle-tracker-stencil-habit-tracker-stencil-unique-design-stencil-cleaning-tracker-stencil

Erin Floto has a metal stencil for a chronodex circular design for use in bullet journals. It's a form of circular calendar with the inner circle containing space for daily, bi-weekly, weekly, monthly and longer time horizons with succeeding rings of the circle containing space for data related to the inner categories. Some of the exterior rings also include numbered squares representing days of the month or week on which a task should be done or for which a habit on an interior part of the circle might be tracked.

The chronodex, a portmanteau of chrono (time) and index, idea is fairly simple, but can be quite complex. For actual use, one may need to be able to spin the visualization around to read and understand it.

Other stencils with habit trackers, etc: https://erinflotodesigns.com/collections/metal-stencils