STEP 18
Fold up the top flap on the open end, so that the tip of the lower flap reaches the tip of upper flap...
STEP 19
Fold two of the flaps over and repeat step 18 for the other lower flap.
STEP 20
Fold one flap over and lay flat...
...to get this.
STEP 21
.Fold the top flap down...
....to get this.
STEP 22
Flip the paper over and repeat step 21 for the other side.
Origami by Aidan Dysert