It was a bit tricky to fold cleanly on the first go for me. I just tried it with US "Letter" paper (8.5 x 11) instead of the A/B size mentioned. To compensate

It was a bit tricky to fold cleanly on the first go for me. I just tried it with US "Letter" paper (8.5 x 11) instead of the A/B size mentioned. To compensate for the different aspect ratio, I used 4x4 folds instead of 4x6. It worked out nicely.