Unpacking

[Inferdy]

Is there a way to get the right detailed 13x13 pixels scheme from the initial 3x3 representation?

[mxgmn]

You can do it with the map node:

<sequence values="WO" symmetry="()">
  <one in="WWW/WWW/WWW" out="***/*OO/***"/>
  <map scale="13/3 13/3 1" values="BWO">
    <rule in="W" out="BBBB/BWWW/BWWW/BWWW"/>
    <rule in="O" out="BBBB/BOOO/BOOO/BOOO"/>
  </map>
</sequence>

[Inferdy]

Wow, it's so cool. I wish I knew it before I started my WIP project 😂