• Start from M_RmRmRvUvDmLmDvUm
• Locate a sequence of four consecutive tiles (A, B, C, D) hinged about parallel sides and foldings of (in order) valley, valley, mountain type
• By slightly opening the structure change the folding between B and C from valley to mountain, tiles A and B are stacked together in the process
• Turn the newly formed flap 90 degrees into the final shape