Step 1:
Glue two paper squares together or cut a large square in half.
Fold over the yellow line.

Step 6:
Prefold into 3 parts of the same size.

Step 5:
Fold all lines into the same direction.

Step 2:
Prefold in half.

Step 4:
Fold to the centerline and unfold the model.

Step 3:
Fold the edges to the centerline.

Step 10:
Fold to the left, the mountain-fold is already prefolded.

Step 8:
Prefold over these 3 lines, the upper line is already prefolded in step 6.

Step 9:
Fold to the left, the mountain-fold is already prefolded.

Step 7:
Prefold the edge to the prefolded line.

Step 16:
Make a sharp folding line at the bottom.

Step 15:
Fold all eight parts of the edge downwards

Step 12:
Glue the marked parts to the other end

Step 11:
Repeat steps 9 and 10 seven more times.

Step 14:
Fold this spot downwards over the prefolded line.

Step 13:
Press downwards by folding over the prefolded lines.

Step 17:
Glue the edges together.