We recommend thin and soft paper such as news paper or advertisement paper. Fold each of the corners meet the creased center.
Form is pentagon.
Then open your finger to open the part and press the top portion of the open it by your other hand and top crease line meet the bottom center line. Folded potion will make right angle both side. Fold left corner to meet right corner and it will become right angled triangle. For ready to make sound, hold the bottom sharp angled portion as shown. QuickTime is need to see below operartion.