I was originally drawn to this model because of the hexagrid details (I mean, who doesn't love hexagrid?) but as I started exploring the model I found some inconsistencies and a design choice or two that were tripping Fusion360 up when the model was recalculated for different numbers of decks.

I'm not sure I completely solved those problems, but it has been an interesting exploration and learning experience.

For example, when changing from 2 decks to 1, Fusion consistently resolves tangencies on the base incorrectly leading to unexpected results.  My current workaround is to set Decks to 1.5, then to 1.

When changing the "Decks" parameter value, you will still need to revisit the two extrude features that cut the side and end hexes to clear the selection and reselect the appropriate hexagons to cut away.

Explore the sketches, I tried to use the parameters and formulas as much as made sense to maintain relationships between features.

The included STL files are for standard poker-sized playing cards, using 6mm x 2mm magnets.

I'll update the model as I find ways to improve it.