I recommend printing with the first layer at 20% speed without supports; this is already set in the .mf3 and .gcode files.
The magnets I used were 5mm diameter and 2mm height.
You will most likely need to put a little super glue in each magnet hole.
Each piece is less than 20mm in length and width and should fit this chess board which you can print using your paper 2D printer. ;)
Openscad files are also included if you need to make and modifications (e.g. the magnet size).
The author hasn't provided the model origin yet.