A3 In Photoshop. The extra 5 mm on each side will be cut off after printing. See if that works.
In photoshop create a slightly wider format such as 307 by 430 or vice versa. Specify a file name prefix. Entering a Width value automatically sets the Height value.
In Photoshop select File Export Artboards To Files.
Dividing a canvas into regions with photoshop. Close the image file. If I wanted the height to be exactly 4 inches I could change the Height value to 4 inches which would then change the Width to 6001 inches. After choosing the Landscape 8 x 10 preset we see that sure enough this preset will create a document with a Width of 10 inches and a Height of 8 inchesIt also sets the Resolution to 300 pixelsinch which is the standard resolution for print.