1. Material preparation: For large cardboard, it is recommended to use 5mm thick high-density cardboard, scissors and cutting tools, protractor, ruler and compasses, and binding materials such as metal rings or glue.

Second, the steps:

1. Design and draw the calendar shape and internal card style according to your own needs.

2. Use a cutting tool to cut out the shapes of various parts, including the base, posts and cards. Among them, the cards need to be divided into corresponding groups according to the calendar time.

3. Cut and arrange all parts, and punch holes at corresponding positions.

4. Use a protractor and compasses to measure and mark the dimensions and angles of columns and bases.

5. Insert the finished card into the hole of the post. It is necessary to set different column heights according to different card groups to ensure smooth time display of the calendar.

6. Fix the base and column with adhesive material. Finally, the completed card can be inserted into the corresponding column.

Extended data:

1. When designing and selecting card styles, you can customize them according to your own preferences and calendar usage occasions. You can choose different colors, pictures, patterns and other elements to present your own calendar. In addition, if you want to add some interactivity and fun, you can also design some small games and interesting questions on the cards.

2. When cutting and assembling, ensure the symmetry and accuracy of all parts, so as not to affect the use effect of the calendar. At the same time, we should pay attention to the quality and hardness of the material to avoid the situation that the card can't be inserted into the column or the base can't bear it.

Although it seems simple to make a three-dimensional calendar, it actually takes some time and patience. If it is the first time to try to make it, it is suggested that you can refer to some related tutorials or videos and learn some skills and methods in order to better complete the production process.

In a word, making a unique three-dimensional calendar is an interesting and challenging creative DIY project. Handmade can not only exercise our hands-on ability, but also let us enjoy the fun of self-creation.