Case for 1 card;
The size of the inner rectangle after printing with the 0.4mm nozzle at standard settings(Super quality; UltiMaker Cura), will correspond to the size of a standard card (length - 85.6 ± 0.13 mm, width - 53.98 ± 0.06 mm).
QR will detect you to the - scp wiki

(!!Warning, if you want to print this with resin, the center on the cutout side will warp after post-curing.!!)