11.
Apply (1) valley, (2) mountain, (3) valley, (4) mountain, (5) valley-folds of the step #10 in order.
Prepare to apply (1) valley, (2) mountain, (3) valley, (4) mountain, (5) valley-folds in order to other side.
12.
Apply (1) valley, (2) mountain, (3) valley, (4) mountain, (5) valley-folds of the step #11 in order.
Prepare to open the paper.