[up to this 3D shape]
- Start from
- Close it in a 3x1 vertical rectangle made of a stack of four tiles in the lowest position
and two stacks of two tiles
- Open it vertically in a 3x2 rectangle with two stacks of two tiles in the lowest row
- Turn up 90 degrees the top tile of the left stack of two tiles about its right vertical side (valley fold).
Note: act specularly from now on if this move is not possible
- Turn down 90 degrees the bottom tile of the right stack into the final shape
