<ul>
<li>Start from RRmRvURRvRmU
<li>Close into a 2x2 square with stacks of three tiles in positions North-West and South-East,
a single tile at first floor in position North-East and a single tile at third floor in position
South-West of type <i>slash</i>
<li>Open in 3D with the following hingings
 <ul>
  <li>South side for the top two tiles in the North-West stack (giving rise to a flap)
  <li>West side for the bottom two tiles in the North-West stack
  <li>South side for the the top two tiles in the South-East stack
  <li>West side  for the bottom two tiles in the South-East stack
 </ul>
<li>Open in the final shape
</ul>