Just for fun, I wrote a small loop to define font-related single-letter commands, such as \cA = \mathcal{A} and so on.
It is based on this answer by David Carlisle on TeX.SE.
Here it is!
%%% Dark magic
\makeatletter
\def\font@loop#1{% define a loop
\ifx\relax#1% if we get to \relax, do nothing
\else% otherwise...
% define \cA=\mathcal{A}, etc
\expandafter\def\csname c#1\endcsname{\mathcal{#1}}
% define \sA=\mathsf{A}, etc
\expandafter\def\csname s#1\endcsname{\mathsf{#1}}
% define \bA=\mathbf{A}, etc
\expandafter\def\csname b#1\endcsname{\mathbf{#1}}
% define \fA=\mathfrak{A}, etc
\expandafter\def\csname f#1\endcsname{\mathfrak{#1}}
% define \AA=\mathbb{A}, etc
% warning: \AA and \SS are predefined LaTeX commands!
\expandafter\def\csname #1#1\endcsname{\mathbb{#1}}
\expandafter\font@loop%
\fi}
% call the loop
\font@loop ABCDEFGHIJKLMNOPQRSTUVWXYZ\relax
\makeatother
It’s not pretty but it’s (in my opinion) a better alternative than writing down manually the different commands necessary.