Drag to rotate · Ctrl + wheel to zoom · 50 mm grid
Lanes and dividers
Each column is one lane of the box, left to right; dividers run front to back. The number is how many cards sit behind each divider (the starting ones are examples). Enter adds the next one.
Print at 100% (actual size), with fit-to-page turned off. The 50 mm ruler at the foot of each sheet lets you check the scale. The divider design is changed in the settings panel.