%%
%% The LaTeX Companion, 3ed
%%
%% Example 12-2-4 on page II-237 in "bm --- Making bold".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{99.0pt}
%
% Special setting to make delimiters always grow in this example
\setlength\delimitershortfall{-3pt}

%StartShownPreambleCommands
\usepackage{newpxmath,bm}
%StopShownPreambleCommands

\begin{document}
$\bm{\Biggl\lbrace\biggl\lbrace\Bigl\lbrace\bigl\lbrace \lbrace
     \mathcal{Q}
     \rangle \bigr\rangle\Bigr\rangle\biggr\rangle\Biggr\rangle}$
\end{document}