For the life of me I can’t find the post that got me intrigued by this design. (thanks @cynd11 for finding @bmcgrain’s post which you link later.) Someone was going to do it parametric in Fusion. I wanted to try it in Inkscape. Worked up the design yesterday and tested in cardboard. Tried to print it in Proofgrade, but I’m still trying to get the settings dialed in for my early pre-release. I tweaked the sizing to use a full bed of material and make it one print. It might not be the most pleasing design, but It would work for a quick gift or maybe a manipulative for kids learning the days and months and how to keep track of calendar time.
I put a few colors in here mainly so you can turn off parts of the design to use up scraps. The pink engraving is for a relief so the rings will slid since the spacers are the thickness of the moving rings. There are many different examples of this type of calendar.
Here is a cardboard version. The smaller circle, the football shape and the three small arcs are the spacers in between bottom and top plates.
Spacers on top of bottom plate.