\documentclass{article}

\title{Dot Paper}

\usepackage{geometry}
\geometry{letterpaper, margin=0mm}

\usepackage{tikz}
\tikzset{x=1mm, y=1mm}

\definecolor{DotsColor}{HTML}{C9C9C9}

\begin{document}

\newsavebox{\frontside}
\savebox{\frontside}
{
	\begin{tikzpicture}[remember picture, overlay]

	\color{DotsColor}

	\foreach \x in {0,...,42}
		\foreach \y in {0,...,56}
			\filldraw (current page.south west) ++ (33.95,237.7) ++ (4*\x,-4*\y) circle (0.1);

	\end{tikzpicture}
}

\usebox{\frontside}

\end{document}