1.  Start with your printed sheet of A4
  2.  Fold in half along the long length
  3.  Fold in half again along the short length
  4.  Fold in half again along the short length again
  5.  You now have a small folded sheet
  6.  Unfold it all back to the full size A4 sheet, now with lots of crease lines in it
  7.  Fold in half across the middle. Make a mark in the centre of the page, then cut from the folded edge, through both sides of the paper, only as far as the mark!
  8.  Unfold it again to original size, and it should look like the picture above with a slit running partway across the middle. Fold in half along the long length again
  9.  Push the folded edges towards the centre, allowing the slit to open up into a diamond shape
  10.  Keep pushing the edges towards the centre until the diamond disappears into another slit, but running perpendicular to the folded edges
  11.  Keeping the slit tightly closed, fold over the four sides to make one small booklet in the correct page order
  12.  Finished!