In the past, I have printed 3x3 grids assembled together like puzzles.
But it became complicated to bind depending on the printing quality.
Additionally, 3x3 becomes restrictive depending on the size of the table.

This is why I preferred to make 2x2s and add small magnets on each side to keep them connected.
It works perfectly, so I'll provide you with all that.

REQUIREMENT

• 4x Round neodymium magnet 1x1mm
• Glue (superglue for me)
• Permanent marker
• Tweezers

INSTRUCTIONS

• Stick a first magnet (flat face) in one of the holes
• Once the glue is dry, put a magnet on the one already glued
• Use the marker on the flat side to know the direction of polarization
• Retrieve this magnet
• Stick it in the second hole (same side of the grid), so that the marked side is not visible

For the next side of the grid, repeat the steps to mark a magnet. Each face must keep the same polarity on the top hole, the same for the bottom holes.

This means that the magnet marked on the top one must be placed marked face up on the top hole of the next face of the grid. Without this, the different grids will not attract each other (on the contrary).

With superglue, it is best to put the magnet on first, before applying the glue to it. For slow setting glues, it is preferable to do the opposite.