[up to this 3D shape]
- Start from
and orient it as in the picture
- Close the two "ears" on top of the adjacent roof tile (call it A) obtaining a
stack of three tiles
- Change both the hinging sides between the three stacked tiles and
lower tile A
- The roof tile adjacent to A will be moved against a vertical tile
- This frees a flap to be turned 90 degrees into the final position
