A fully 3D printed calendar. No Magnets, no bolts, no glue and no screws are needed. Just 3D printed parts. 
If you don't have an AMS unit, you can just print the date/month tiles in one color - Then you use a Posca Marker or similar to add the date and months.

I seperated each color print (besides the date/months tiles) to individual print plates. Please move these around as you please for faster or more eficient prints.