games – Looking for a visual solution to connect some boxes in a grid where address matters

I have 9 boxes, each 1.5 cm high and wide. I want to place these pictures on a grid (for the sake of simplicity, let's put them on a 3×3 grid). The total size that my grid can support is about 7×7 cm.

Then, I would need to connect some of these boxes to the grid, somehow, where the address matters.

For example, if I get the following grid:

|1|2|3|
-------
|4|5|6|
-------
|7|8|9|

For example, you would need to connect the box with the ID 6 to the box with id 3 Y 5, representing that you can travel from 6 to 3 Y 5 but not vice versa (you cannot travel from 3 to 6 and neither of 5 to 6)

My connections will always have to be unidirectional, so there can be no connection between 6 Y 5 if there is already a connection of 5 to 6.

I hope I have not complicated my question too much, and it is understandable 🙂 I would prefer a solution that uses the white space between the squares in the grid (I know that the allocated space is quite small), because there will be icons in every four corners of the boxes.

These boxes would be placed on a card for a physical board game, so the end result should be visible when printed.

Anyone have any ideas on this?