Start with a piece of 12" x 12" piece of Cardstock.
Score at 2' and 10" (top/bottom)
Flip and score at 3-1/2", 5-1/2", 9", 11".
Cut the score lines at the bottom to form base.
Cut off all tabs at the top except one. The one left makes the flap for the bag,
Use one of the other cut off pieces, to flip over, and make contrast decoration.