<ul>
<li>Start from RRURmRvRvRmU
<li>Assume that the top tile of the bridge is of <i>slash</i> type, otherwise continue specularly
<li>Fold down the "bridge" with all three tiles stacked in a single pile and the East
    vertical tile ending up on top (third floor).
<li>Fold left the two eastern tiles (valley fold) ending up with a 2x2 square
<li>Rotate it such that in the north row we have a stack of 2 tiles (West) and 1 tile (East),
    whereas in the south row we have a stack of 4 tiles (West) and 1 tile (East)
<li>Now open in 3D with the following hinging:
 <ul>
 <li> the two stacked tiles in the North-West position are hinged along the North edge
 <li> the upper two stacked tiles in the south-West position are hinged along the West edge
 <li> the two middle stacked tiles (SL) hinged East
 <li> the two lower stacked tiles (SL) hinged South
 </ul>
<li>End up with the final shape
</ul>