I built this to fit 60x10x3mm magnets to make a magnetic latch.
I tried to minimize the spacing between the magnets by making a single layer thickness on each side, which make the layer fragile, so be careful and make sure the magnets are correctly oriented before you insert them. #4 or #6 screws work best.
https://www.amazon.com/dp/B09FSWDBLV
The author marked this model as their own original creation.