1. Pinch center of bottom edge and pivot upper-right corner around upper-left corner till it meets the pinch line
2. Fold right half onto left half while moving the corner from pinch line onto upper-left corner. The end result is like an inside reverse fold at 60° in the upper left corner.
3. Open the “reverse fold”
4. Squash fold at the bottom while folding along the color-white boundary
5. Valley-fold the flap
6. Valley-fold. Unit is finished.
7. Back side of finished unit
8. For connecting the units, partially unfold the flaps
9. Inserting a flap (the other one, on the left side of unit) into a pocket
10. Flap fully inserted
11. Start folding along precreased lines, with the other unit’s flap locked between layers
12. Hide the folded flap beneath top layer
13. Two units fully connected. Now continue adding more units, for a total of 6.
14. Finished model, front
15. Finished model, back
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