How can I write fancy-looking Roman numerals?

\documentclass{article}
\usepackage{stackengine}
\setstackEOL{\\}
\newcounter{tmpctr}
\newcommand\fancyRoman[1]{%
  \setcounter{tmpctr}{#1}%
  \setbox0=\hbox{\kern.2pt\textsf{\Roman{tmpctr}}}%
  \setstackgap{S}{-.6pt}%
  \Shortstack{\rule{\dimexpr\wd0+.1ex}{.7pt}\\\copy0\\
              \rule{\dimexpr\wd0+.1ex}{.7pt}}%
}
\begin{document}
Fancy Romans:

1--5: \fancyRoman{1}
\fancyRoman{2}
\fancyRoman{3}
\fancyRoman{4}
\fancyRoman{5}

6--10: \fancyRoman{6}
\fancyRoman{7}
\fancyRoman{8}
\fancyRoman{9}
\fancyRoman{10}

11--12: \fancyRoman{11}
\fancyRoman{12}
\end{document}

I have used, instead, an old package called romanbar package to write roman numbers where you can see also the macro of the user @egreg that it is the same of the link of the comment below the question,

Here there is my small code:

    \documentclass[12pt,a4paper]{article}
    \usepackage{newtxtext}%%%%%%%%%%%% <----optional (it gives a best view of the roman numbers) - 
%%%% You can choose another font compilable with pdfLaTeX
    \usepackage{romanbar}
    \begin{document}
    \Romanbar{1}, \Romanbar{2}, \Romanbar{5}, \Romanbar{10}, \Romanbar{43}
    \end{document}