neodotfiles/local/share/icons/Papirus/symbolic/actions/tool-rectangle-symbolic.svg

<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" version="1.1">
 <path style="fill:#444444" d="M 1,1 V 15 H 15 V 1 Z M 3,3 H 13 V 13 H 3 Z"/>
</svg>