documentclass{beamer}
usepackage{etex}
usepackage{tikz}
usepackage{pgfplots}
usetikzlibrary{backgrounds, decorations.fractals, spy}

begin{document}

begin{frame}[plain]
    begin{tikzpicture}[spy using overlays={size=12mm}]
        draw [decoration=Koch snowflake] decorate { decorate{ decorate{ decorate{ (0,0) -- (2,0) }}}};
        spy [green,magnification=3] on (0.6,0.1) in node at (-0.3,-1);
        spy [blue,magnification=5] on (1,0.5) in node at (1,-1);
        spy [red,magnification=10] on (1.6,0.1) in node at (2.3,-1);
    end{tikzpicture}
end{frame}

end{document}