\PGset[0.8em]
\begin{picture}(16,10)

\drawline(1,1)(15,1)(15,9)(1,9)(1,1)

\drawline( 3,1)( 3,9)
\drawline( 5,1)( 5,9)
\drawline( 7,1)( 7,9)
\drawline( 9,1)( 9,9)
\drawline(11,1)(11,9)
\drawline(13,1)(13,9)

\drawline(1,3)(15,3)
\drawline(1,5)(15,5)
\drawline(1,7)(15,7) 

\end{picture}
\PGrestore