\def\thetitle{}
\def\thecomposer{}
\def\theinstrument{}
\def\title#1{\def\thetitle{#1}}
\def\composer#1{\def\thecomposer{#1}}
\def\instrument#1{\def\theinstrument{#1}}

\def\maketit{
  \begin{center}
    {\Large\bfseries\thetitle}\\
    \vskip12pt
    {\bfseries\theinstrument}\hfill{\scshape\thecomposer}
  \end{center}
  \bigskip
  }