Avec tikz Ti*k*Z : on peut reprendre le code qui crée les accolades (decoration=brace (`decoration=brace` ou, comme ci-dessous, decoration=calligraphic brace) `decoration=calligraphic brace`) et prolonger ("à (« à la main") main ») les extrémités :
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing,calligraphy,calc}
\makeatletter
%% cf. tikzlibrarycalligraphy.code.tex
\pgfdeclaredecoration{my calligraphic brace}{brace}
{
\state{brace}[width=+\pgfdecoratedremainingdistance,next state=final]
{
\pgfsyssoftpath@setcurrentpath{\pgfutil@empty}
\pgfpathmoveto{\pgfpointorigin}
\pgfpathmoveto{\pgfqpoint{1mm}{-2mm}} %% cette ligne modifie le point de départ
\pgfpathcurveto
{\pgfqpoint{.15\pgfdecorationsegmentamplitude}{.3\pgfdecorationsegmentamplitude}}
{\pgfqpoint{.5\pgfdecorationsegmentamplitude}{.5\pgfdecorationsegmentamplitude}}
{\pgfqpoint{\pgfdecorationsegmentamplitude}{.5\pgfdecorationsegmentamplitude}}
{
\pgftransformxshift{+\pgfdecorationsegmentaspect\pgfdecoratedremainingdistance}
\pgfpathlineto{\pgfqpoint{-\pgfdecorationsegmentamplitude}{.5\pgfdecorationsegmentamplitude}}
\pgfpathcurveto
{\pgfqpoint{-.5\pgfdecorationsegmentamplitude}{.5\pgfdecorationsegmentamplitude}}
{\pgfqpoint{-.15\pgfdecorationsegmentamplitude}{.7\pgfdecorationsegmentamplitude}}
{\pgfqpoint{0\pgfdecorationsegmentamplitude}{1\pgfdecorationsegmentamplitude}}
\pgfpathmoveto{\pgfqpoint{0\pgfdecorationsegmentamplitude}{1\pgfdecorationsegmentamplitude}}
\pgfpathcurveto
{\pgfqpoint{.15\pgfdecorationsegmentamplitude}{.7\pgfdecorationsegmentamplitude}}
{\pgfqpoint{.5\pgfdecorationsegmentamplitude}{.5\pgfdecorationsegmentamplitude}}
{\pgfqpoint{\pgfdecorationsegmentamplitude}{.5\pgfdecorationsegmentamplitude}}
}
{
\pgftransformxshift{+\pgfdecoratedremainingdistance}
\pgfpathlineto{\pgfqpoint{-\pgfdecorationsegmentamplitude}{.5\pgfdecorationsegmentamplitude}}
\pgfpathcurveto
{\pgfqpoint{-.5\pgfdecorationsegmentamplitude}{.5\pgfdecorationsegmentamplitude}}
{\pgfqpoint{-.15\pgfdecorationsegmentamplitude}{.3\pgfdecorationsegmentamplitude}}
{\pgfqpoint{-1mm}{-2mm}} %% cette ligne modifie le point d'arrivée
}
\tikzset{
taper width=.5\pgflinewidth,
taper
}%
\pgfsyssoftpath@getcurrentpath\cal@tmp@path
\MakeSPathList{calligraphy path}{\cal@tmp@path}%
\SPathListPrepare{calligraphy path}%
\CalligraphyPathCreate{calligraphy path}{copperplate}%
}
\state{final}{}
}
\makeatother
\begin{document}
\begin{tikzpicture}
\draw (0,1) node[draw] (2) {2};
\draw (3,1) node[draw] (3) {3};
\draw[decoration={my calligraphic brace,amplitude=4mm,mirror,raise=-1mm},decorate,line width=1.3pt] ($(2.south west)+(-2mm,0)$) -- ($(3.south east)+(2mm,0)$);
\end{tikzpicture}
\end{document}
![alt text][1]
[1]: https://texnique.fr/osqa/upfiles/accolades.png<img src="/upfiles/accolades.png" style="width: 100%;"/>