Step 1.

Take a square sheet, place it flat on the table, with the bottom edge horizontal.

additional information

  • The corners of the square are: top left, top right, bottom right, and bottom left.

Step 2.

Make a valley fold, vertical, by bringing the right edge over to the left edge.

Crease the fold well, then unfold.

additional information

  • This just marked the vertical axis of symmetry.

Step 3.

Make a valley fold, vertical, by bringing the right edge along the valley fold corresponding to the vertical axis of symmetry.

Crease the fold well, and leave it folded.

Step 4.

Make a valley fold, vertical, by bringing the left edge along the valley fold corresponding to the vertical axis of symmetry.

Carefully crease the fold, and let it fold.

additional information

  • You get a vertical rectangle with two double-thickness rectangular flaps (one right and one left).
  • On the front side, a slit follows the vertical axis of symmetry.

Step 5.

Form a valley fold, horizontal, by bringing the bottom edge up to the top edge.

Carefully crease the fold, then unfold.

additional information

  • This just marks the horizontal axis of symmetry.

Step 6.

Form a valley fold, horizontal, by bringing the bottom edge up along the valley fold corresponding to the horizontal axis of symmetry.

Carefully crease the fold, and let it fold.

Step 7.

Form a valley fold, horizontal, by bringing the top edge down along the valley fold corresponding to the horizontal axis of symmetry.

Well score the fold, and let it fold.

additional information

  • The folding is a square with quadruple thickness.
  • The front top flap, double thickness, is a horizontal rectangle, its top edge is a hinge edge, which connects it to the base square.
  • The front bottom flap, double thickness, is a horizontal rectangle, its bottom edge is a hinge edge, which connects it to the base square.
  • The two front flaps meet, forming a slit along the horizontal axis of symmetry of the shape.

Step 8.

Create an oblique valley fold (through all layers), bringing from bottom to top towards the left, the bottom right corner, onto the top left corner.

Well score the fold, then unfold.

Step 9.

Form an oblique valley fold (through all layers), bringing from bottom to top on the right, the lower left corner, onto the upper right corner.

Firmly crease the fold, then unfold.

Step 10.

Tilt the front bottom flap to vertical.

Slide the right index finger between the two layers, along the vertical valley fold on the right.

Slide the left index finger between the two layers, along the vertical valley fold on the left.

Push simultaneously, the right index finger to the right, and the left index finger to the left.

Then fold down the flap currently vertical against the fold.

additional information

  • The front lower flap, which was rectangular, has been transformed into a horizontal trapezoid.

Step 11.

Rotate the folding by half a turn, without flipping it over.

additional information

  • the trapezoid-shaped flap is now the front upper flap.

Step 12.

Apply to the front lower flap the manipulations described in step 10.

additional information

  • The base of the windmill is ready.
  • It is a symmetrical 6-sided shape.
  • the top and bottom edges are horizontal.
  • the back face (against the table) is a square.
  • the front face consists of two horizontal trapezoids, whose large bases meet along the horizontal axis of symmetry.
  • The right and left parts are triangular in shape, built around two independent double-layered symmetrical triangles, separated by a horizontal slit.