mod_icon.tex

\documentclass[12pt]{article}

\usepackage{geometry}

\usepackage{fontspec}
\usepackage{polyglossia}
\usepackage{unicode-math}

\usepackage{tikz}

\setmainlanguage{english}
\setotherlanguages{greek}

\setmainfont{Times New Roman}
\setmathfont{Cambria Math}

\newfontfamily\Cambria{Cambria}[Scale=MatchLowercase, Ligatures=TeX]

\begin{document}
    \newcommand{\sh}[1] {
        \node [draw] (A) at (2.8, 0) {};
        \node [draw] (B) at (3.2, 0) {};
        
        \node [draw] (U) at (2.6, 0.6) {};
        \node [draw] (W) at (3.4, 0.6) {};

        \draw (U) -- (A) -- (B) -- (W);

        \node [draw] (Z) at (0, 2.8) {};
        \node [draw] (Q) at (0, 3.2) {};

        \node [draw] (S) at (0.6, 2.6) {};
        \node [draw] (T) at (0.6, 3.4) {};

        \node [draw] (P) at (6, 2.8) {};
        \node [draw] (R) at (6, 3.2) {};

        \node [draw] (P) at (5.4, 2.6) {};
        \node [draw] (R) at (5.4, 3.4) {};

        \node [draw] (X) at (2.6, 5.4) {};
        \node [draw] (Y) at (3.4, 5.4) {};

        \node [draw] (C) at (2.8, 6) {};
        \node [draw] (D) at (3.2, 6) {};

        \draw (C) -- (D);

        \begin{scope}[xshift=3cm, yshift=3cm]
            \node [draw] (J) at (35: 2.4) {};
            \node [draw] (G) at (55: 2.4) {};

            \node [draw] (D) at (40: 3) {};
            \node [draw] (F) at (50: 3) {};

            \node [draw] (E) at (125: 2.4) {};
            \node [draw] (EE) at (145: 2.4) {};

            \node [draw] (N) at (130: 3) {};
            \node [draw] (M) at (140: 3) {};

            \node [draw] (UI) at (215: 2.4) {};
            \node [draw] (IU) at (235: 2.4) {};

            \node [draw] (O) at (220: 3) {};
            \node [draw] (I) at (230: 3) {};
        \end{scope}
        
        \draw (3,3) circle [radius=2.4];
    }
    \begin{tikzpicture}
        \node[black,rectangle] (A) at (0,0) {$\mathcal{L}$agrangian[$\textgreek{φ}_i (<$};
        %⚙, ⚙>)$]
        \sh{a}
    \end{tikzpicture}
\end{document}