Single tex source for article and beamer slides

main.tex

% Ever wanted to turn your latex article source into a quick beamer presentation?
% Add something like the following four lines to the beginning of your document:

%\documentclass{amsart}
%\renewenvironment{frame}{{}}
\documentclass[ignorenonframetext,red]{beamer}
\geometry{paperwidth=480pt,paperheight=300pt}

% Then those parts you want turned into slides wrap with \begin{frame} ... \end{frame}