Start with the plain side of a square piece of paper up. Fold the paper in half.
Fold the top corners towards the bottom point and then open to create these creases.
Fold both layers of the bottom point up to the top of the model and then open.
This is one complete unit; you need three. So, make 2 more.
Insert one unit inside the other and then link the units all together.
Your triangle box is ready.
