<ul>
<li>Start from L1 and
open it into RRmRRmRUmDUm
<li>Position it as in picture
<li>Lower the "roof" to the right by rotating two vertical tiles 90 degrees and translating the two
roof tiles to the right and down
<li>Rotate down 90 degrees the two superposed tiles against another tile to form a stack of three tiles
<li>This will free the inner tile of the stack, that can be rotated towards the front bringing forward
also the two tiles originally on the back wall.
<li>The tile originally on the left lateral wall becomes a flap to be rotated up 90 degrees
<li>Now push the newly formed vertical walls, one on the left, the other on the right (chose the
inner one of the two stacked tiles), against each other bringing together also the two adjacent
tiles.
<li>We end up with two pairs of vertical stacked tiles, the pair on the right can be lowered by
rotating both tiles right by 90 degrees.
<li>We have now a single stack of two tiles, the tile on top can be raised 90 degreed <b>inside</b>
the 'tube' to obtain the final shape.
</ul>