<ul>
<li>Start from RRmUmDUmRvLmRv
<li>Deform the shape by slightly pushing the internal side of the far vertical wall and
pushing up the internal side of the top horizontal roof
<li>Simultaneously open the two flaps untill they become coplanar and make them
stack onto adjacent nearby tiles
<li>By insisting with the deformation arrive into a flat shape made of three stacks
of tiles (in the shape of a gnomon)
<li>The two tiles that were originally flaps are now adjacent and can be rotated 180 degrees
<li>By opening the resulting structure you get the final shape
</ul>