documentclass{standalone}
usepackage{tikz}

begin{document}

  % Define frets
  tikzstyle{fret} = [draw,fill=blue!20,minimum size=3em]

  begin{tikzpicture}
    % dist( x ) = s / ( 2 ^ ( x / d ) )
    defd = {12}
    defs = {651mm}
    % dist( x ) = 651 mm / ( 2 ^ ( x / 12 ) )

    % Draw nodes, etc.
    % Strings
    foreach a/b in {1/E, 2/B, 3/G, 4/D, 5/A, 6/E} {
      node at (0,-a) (inputa) {$b$};
      % Frets
      foreach x in {1,...,24} {
        node[fret] at (x,-a) (blocka) {$x$};
    }
  }

end{tikzpicture}
end{document}