The author remixed this model.
I changed the saggings for the screws to DIN 912 hex cap screws, because this type of screws are more common than the countersunk head-screws. For this i did increase the thickness of the button plane.
Additionally I changed the dimensions and the design of the cover for the connector and combine this to the main button part so this is one unit.
I also increase the pocket in the main button part for the GPIO soldering pins on the underside of the pi zero and add two more pockets for the nuts or screw caps of the stand-offs.
Over all now the pi zero and the HAT fits perfectly in the case.