Change beamer theme mid document

Question

Is it possible to change beamer theme mid document or do you have to make two pdfs and stick them together?

Answer 1

beamer themes (main themes as well as color, font, inner and outer themes) may not be switched mid-document. However, it is possibe (though perhaps not always desirable) to change beamer's internal settings in accordance with a desired new theme. In the following example, I mimic a switch from the default settings to that of the "orchid" color theme.

\documentclass{beamer}

\begin{document}

\section{First}

\begin{frame}{First}
\begin{theorem}
Some text.
\end{theorem}
\end{frame}

\setbeamercolor{block title}{use=structure,fg=white,bg=structure.fg!75!black}
\setbeamercolor{block title alerted}{use=alerted text,fg=white,bg=alerted text.fg!75!black}
\setbeamercolor{block title example}{use=example text,fg=white,bg=example text.fg!75!black}

\setbeamercolor{block body}{parent=normal text,use=block title,bg=block title.bg!10!bg}
\setbeamercolor{block body alerted}{parent=normal text,use=block title alerted,bg=block title alerted.bg!10!bg}
\setbeamercolor{block body example}{parent=normal text,use=block title example,bg=block title example.bg!10!bg}

\section{Second}

\begin{frame}{Second}
\begin{theorem}
Some text.
\end{theorem}
\end{frame}

\end{document}

Answer 2

Package colourchange allows you change colortheme inside a presentation.