How to Fold a Penultimate Module

Folding the Module

1. 1
   Place a square piece of paper with the color side down.
   
   
   
2. 2
   Fold it in half.
   
   
   
3. 3
   Unfold; there should now be a crease down the middle.
   
   
   
4. 4
   Fold the edges parallel to this crease into the center.
   
   
   
5. 5
   Valley-crease the middle fold so the flaps are on the outside. Your paper is now divided into fourths.
   
   
   
6. 6
   Fold the bottom-left corner up so it meets the top edge.
   
   
   
7. 7
   Turn the paper 180 degrees and repeat.
   
   
   
8. 8
   Fold from the bottom-left corner to the upper-right corner.
   
   
   
9. 9
   Unfold and now you have your unit!
   
   
   

Assembly

1. 1
   Notice how the edges of the module are "open" like "pockets."
   
   
   
2. 2
   Insert one of the triangular flaps into that pocket. It doesn't matter how many layers there are, just make sure it fits.
   
   
   
3. 3
   Make sure that the two creases outlined in green match up. It should create a locking effect.
   
   
   
4. 4
   Make a triangle by inserting another triangle into the pocket of the second one and let the flap of the first one go into the third one.