Stick one end of the double-sided adhesive tape to the other end. And fold it at the paste place, and the other half will determine the crease at the other end according to the crease at this end.

Open it.

Find the right position, not too narrow and not too wide, and fold the bottom.

So is it up there.

The other end is the same as above.

Then, at the lower end, fold it. Also, neither too narrow nor too wide, the size is controlled by the size of the gift bag.

Expand.

One corner is folded in half to the crease and the other corner is also folded in half to the crease.

Then, stand up.

Fold the creases on both sides inward.

Stick the small triangles on both sides to the bottom with double-sided tape.

Just arrived, the gift package is ready.