Step 7: Collapse the triangles
Bring it to the left, and press it against the layer under it.
Once you did that, open the triangle back up.
Bring the side of the adjacent trapezoid thing over, and cover the left half of the triangle.
Fold the excess paper back so it keeps the "leg" that we created together.
Do it to all four sides (the last side is more challenging than the others, but the method is basically the same. However, if any "leg" becomes loose or opens up, you'll have to fix them. Clipping them temporarily together with something like a paper clip or small peg could be a solution, but...O0O CHEATERS!)