The author remixed this model.
Increased the holes in the holder to accept 10x3mm magnets (snug fit) for a stronger hold. (With these magnets it's less likely that bigger keychains fall out)
Moved the holes at the back (bottom) of the model.
Removed the height differences between the slots.
I used smaller magnets (6x3mm) in the keyholder part for an even stronger hold.