%!
%% Draws a one square inch box and inch in from the bottom left
/inch {72 mul} def % Convert inches->points (1/72 inch)
newpath % Start a new path
1 inch 1 inch moveto % an inch in from the lower left
2 inch 1 inch lineto % bottom side
2 inch 2 inch lineto % right side
1 inch 2 inch lineto % top side
closepath % Automatically add left side to close path
fill % Fill in the box on the paper
showpage % We're done... eject the page