• Start from RRmRmDvLvDRmUm
• Close the "tube" by pushing together the two tiles that lie along the boundary of the bounding box (and the two other tiles of the tube)
• Change the hinging side between the two adjacent tiles that have been pushed together
• This allows to turn 90 degrees a pair of adjacent tiles
• Turn 90 degress a newly formed flap tile into the final shape