[up to this 3D shape]
- Start from L-1
- Turn it upside-down with a 180 degrees rotation about the North-South axis
- By hinging about the top and bottom horizontal sides slide up of one position
all four tiles on top of each stack together with the two 'south' tiles in the
bottom of their stack
- Turn the resulting (flat) shape face-down to obtain a shape with three stacks
of two tiles and two single tiles (on the right).
- Open it in 3D in a manner similar to the 'cube' construction, meanwhile the two East tiles
are subjected to a valley fold
- Lower an internal flap to obtain the final shape.
