If you're looking for calendar for your desk for 2018, beautiful and that is cheap and easy to build nothing like these printable templates to make dodecahedrons. As you may have already thought, there are 12 faces of the regular polygon, one for each month :) In his day we talked about perpetual calendar, which is another good option to manufacture well in wood, paper or cardboard.
The templates of the assemblies in the article are made with the following online tool, very intuitive and easy to use. It's about a dodecahedron calendar generator.
It is very, very simple. You choose between the two types of dodecahedra that it offers, the year of the calendar, language, if you want the week number to appear or not and the format it generates, which can be PDF or postscript and download.