I referred to this as a locking pocket in the title. It isn’t a tato in the traditional sense because it is made from a rectangle and doesn’t have the sort of symmetry that most tatos do. The designer of the fold, Rosemary Lyndall Wemm, calls it a Diagonal Slash Letter Fold. (I attempted to get permission to post the following instructions, but got no response. Her Etsy shop has been closed for a while and she stopped posting in 2014. You can find her original instructions here.)
I made models with 8.5 x 11″ and 8 x 11″ paper. Both worked, so I expect that A4 will work as well. If you are using paper that is coloured/patterned on one side, start with the white/plain side up.
Fold the paper in half horizontally, then vertically. Open flat.
With the paper oriented vertically, fold the two sides in to meet at the middle crease.
Open your paper flat again, then fold the top right corner down to the central horizontal crease. Fold the bottom left corner up to the central horizontal crease.
Fold the upper left section in to the middle. Repeat with the lower right section.
Fold the corner at the top that projects beyond the diagonal fold (at the upper right) down and under to match the line of the angled fold. Repeat with the projecting corner at the lower edge.
Open the left side of your folded paper then refold as shown in the image below. Two crease lines are indicated by pointy fingers. These creases need to be reversed.
Reversing the two folds will make your paper look like the image below. Note that the crease indicated by the green pointy finger in the picture above is now at the side indicated by the green pointy finger in the image below.
Rotate your paper 180° and repeat the previous step.
Tuck the upper right flap (the one with the angled fold on top) under the vertical flap on the left hand side. Rotate your paper 180° and repeat the tuck.
Fold down the upper angled portion of your paper so that the diagonal edge just touches the centre point
Tuck the narrow end into the pocket in the layer below. The pink pointy finger indicates the edge of the pocket.
Rotate 180°, fold, and tuck.
I chose this fold to make the top pockets for a modified Zhen Xian Bao to hold my knitting tools for my recent trip to England. The red pockets on the left hold stitch markers, and the larger blue pocket on the right holds a small pair of scissors and some needles. Although these pockets do not have the fixed sides of a traditional twist box, they are easy to open and close, and do not readily spill their contents if only opened half way.
This design has proven very functional.
Tomorrow I will show you some accordion books with built-in pockets.