\def\visualbox#1#2#3{%
  \hbox{%
    \vrule height#2depth#3\hskip-0.4pt%
    \vbox{%
      \hrule width#1\vskip-0.4pt%
      \vskip#2%
      \vskip-0.4pt\hrule
      \vskip#3%
      \vskip-0.4pt\hrule
      \vskip-#3%
    }%
    \hskip-0.4pt\vrule height#2depth#3%
  }%
}

\def\visualized#1{%
  \setbox0\hbox{#1}%
  \hbox{\copy0\hskip-\wd0\visualbox{\wd0}{\ht0}{\dp0}}%
}

\font\bigtimes ptmr at 40pt
\font\fivett cmtt10 at5pt

\def\myboxes{%
  \visualbox{10mm}{12mm}{4mm}%
  \visualbox{8mm}{10mm}{2mm}%
  \visualbox{15mm}{4mm}{6mm}%
}

\hbox{\myboxes}

\vskip5mm

\def\myvboxes#1#2#3{%
\vbox{%
  \baselineskip#1\lineskip#2\lineskiplimit#3%
  \vbox{\myboxes}%
  \fivett
  \vskip2mm
  \baselineskip6pt\lineskip0pt\lineskiplimit0pt%
  \hsize21mm%
  \parindent0pt%
  \char92 baselineskip\thinspace #1\par
  \char92 lineskip\thinspace #2\par
  \char92 lineskiplimit\thinspace #3\par
  }%
}

\hbox{%
  \myvboxes{12mm}{1mm}{0mm}%
  \myvboxes{9mm}{1mm}{0mm}%
  \myvboxes{3mm}{1mm}{0mm}%
  \myvboxes{3mm}{1mm}{0mm}%
  \myvboxes{3mm}{1mm}{-4mm}%
  \myvboxes{9mm}{1mm}{5mm}%
}

\vskip5mm

\hbox{%
  \hbox to20mm{\visualized{\bigtimes T}\visualized{\bigtimes y}\hfil}%
  \hbox to20mm{\visualized{\bigtimes f}\visualized{\bigtimes i}\hfil}%
}

\hbox{%
  \hbox to20mm{\visualized{\bigtimes Ty}\hfil}%
  \hbox to20mm{\visualized{\bigtimes fi}\hfil}%
}

\vskip5mm
\baselineskip10pt\tt

\def\square{\visualbox{10mm}{10mm}{0mm}}
\def\psquare{\hskip10mm}

\hbox to50mm{\square\hfil\square\hfil\square\hfil\square}
\hbox to50mm{\psquare\hss\char92 hfil\hss\psquare\hss\char92 hfil\hss\psquare\hss\char92 hfil\hss\psquare}

\vskip2mm

\hbox to50mm{\square\hfil\square\hfill\square\hfil\square}
\hbox to50mm{\psquare\hbox to0pt{\hss\char92 hfil\hss}\psquare\hss\char92 hfill\hss\psquare\hbox to0pt{\hss\char92 hfil\hss}\psquare}

\vskip2mm

\hbox to50mm{\square\hss\square\hskip14mm\square\hss\square}
\def\psquare{\hskip9mm}
\hbox to50mm{\psquare\hbox to0pt{\hss\char92 hss\hss}\psquare\hss\char92 hskip\thinspace 14mm\hss\psquare\hbox to0pt{\hss\char92 hss\hss}\psquare}

\bye