Text-Only Instructions
Various sites show how to fold this unit. See, for instance,
Paper to be used: squares of similar size; use large paper to practice with at first.
Thicker paper or thin cardstock is recommended.
Note squares will also make nice, small models, but only use these when you are comfortable with the folding and assembly of these units.
Folding level: Beginner/Intermediate
Steps: 9
Description: A unit or module in origami is like a puzzle piece.
To make a modular origami figure, you will need to fold more than one unit and assemble them in a certain way.
These instructions describe how to fold only one type of unit, the "Sonobe" module, one of the classic units in modular origami.
The method described here is only one way of folding this module. Once the basic unit is folded, it can be modified and connected in different ways to form complex structures.
Many wonderful origami models have been created using this unit.
For instance, once you know how to fold this module, you will be able to combine three of them into what is known as Toshie's Jewel, 6 modules will form a cube or dice, 12 units can be folded into a larger cube or an octahedron, etc.
Just to make matters even more interesting, many variations of the Sonobe unit have been developed as well and units can be folded not only from squares, but also from rectangles, so the basic unit could be a starting point for many other unique modular creations.
If using two-sided origami paper, lay your paper with the patterned or colored side down before starting to fold.
Step 1
Place a square  down  with its edges to the left and right, top and bottom.
Step 2
Fold the top edge down to meet the bottom edge to form a horizontal center crease line.
Crease and unfold.
Step 3
Now fold the top and bottom edges in to meet the horizontal center crease line.
Crease and leave folded.
You will have a figure with an upper and a lower rectangular flap meeting each other along the horizontal center line.
Step 4
Now, fold the top left corner, all the layers, diagonally down to the right as far as it will go. It will line up with the bottom edge of the paper and form a triangle on the left side of the unit.
Crease well and leave folded.
Step 5
Repeat this fold with the bottom right corner of the rectangle.
There will now be 2 triangles that have formed next to each other, pointing in opposite directions.
The outline of the figure will be a more or less rectangular shape, but with points on each side.
Step 6
Unfold the 2 triangles so you have the rectangle again.

Step 7
Notice that you will now have short diagonal valley fold lines at the bottom left and top right corners of the rectangle.
These lines extend only halfway from the corners to the central slit of the rectangle.
Reverse the valley creases so they become mountain folds by folding the bottom left and top right corners inwards so they are hidden within the layers of the paper.
It should look as if a small corner is now missing at the left bottom and top right of the rectangle.
Step 8
Refold and tuck the large left triangle you created in Step 4 under the small corner just below it and then do the same with the large triangle on the right, tucking it in under the small top right corner just above it.
This will lock your Sonobe unit securely so it stays closed.
Important: Always start to fold your large corners in the same way; in this case, the top left and bottom right corners. If you make a modular model and one or more of the units are created with the opposite corners folded in, the units will not fit together.
You will now have a securely locked, long, skinny diamond shape, or to be more accurate, a parallelogram.
Keep the unit with its points at the left and right and with the smooth side facing the table for the explanation that follows:
Step 9
In order to use your Sonobe unit to make modular origami figures, it will help a lot if you can identify the main back and front  parts of the unit and familiarize yourself with its features.
Depending on which type of modular figure you want to make, you will fold your Sonobe unit slightly differently, so for the purpose of this short explanation, the parts of the units will first be described in general terms.
 (A) The Slits or Pockets
If you consider the surface of the module, which we will call the front, you will notice 2 diagonal folds with two loose flaps that face in opposite directions.
These folds  are actually openings, slits or pockets where the points of other modular units will be inserted.
Note that the face or central square of each unit will seem to have 4 diagonal openings, all facing in the same direction and arranged in a kind of pinwheel formation.
 You will always be using the 2 slits that are opposite from each other and that have a single layer of paper.
So, it is worthwhile checking that you can distinguish between the double-layered openings, which will not be used, and the single-layered slits which will be on opposite sides of each unit.
(B) The Central Square
Turn the unit over from left to right and place it so one of its long sides is facing you. The surface of the unit, which we will call the back, should now be smooth.
With the unit in this position, you will be able to identify the central square, with the left triangle  forming a point nearest you and the right triangle forming a point furthest away from you.
This orientation of the parallellogram is important and all your modules should have the central square and points folded in this way.
(C) The Points or Flaps
With the central square placed straight in relation to the edge of the table, you will have a triangular flap on the left, with its pointy end nearest you. On the right, there will be a similar flap, but this one will have its point furthest away from you.
Put in another way, the left triangle will seem to slope downwards from the left side of the central square while the right triangle will seem to slope upwards from the right side of the central square.
These points or flaps will be inserted into the slits or pockets of other similar units.
This completes the explanation of the basic Sonobe unit.
Making origami accessible to visually impaired crafters through text instructions.
for non-commercial use only.
Compiled by Lindy van der Merwe - March 2022
Revised: October 2023