<ul>
<li>Start from L1
<li>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
<li>Turn the resulting (flat) shape face-down to obtain a shape with three stacks
      of two tiles and two single tiles (on the left).
<li>Open it in 3D in a manner similar to the 'cube' construction, meanwhile the two West tiles
are subjected to a valley fold
<li>Lower an internal flap to obtain the final shape.
</ul>