Yeah this stuff can be a steep learning curb.
if you have autodesk inventor or fusion 360, you will find there are source files included for those that wish to mod the original.
I had issues with vibrations eroding cards (I drive an ex military vehicle with hard suspension) and wanted a firm fit to address that.
many people complained which is where the removal holes came from.
but I like close tolerances, and you will find that this is the #1 complaint about this design.
the best bit about printers like this is that you can alter the design or the scale to suit your needs.