Follow instructions from original model: https://www.printables.com/model/512997-gridfinity-box-with-lid-magnetic
Note: These models use the original sizing of the holes for the magnets. On my printer these holes were a bit to small so I had to drill them to the exact size with an M3 drill.
The author remixed this model.
This remix is of size 4x2x12 which wasn't provided by the original author (https://www.printables.com/@PlasticFlow_684486).
Also an additional lid with holes for magnets of size 3x1 mm is provided.