If you have a certain printer to use, you can tweak the Metafont mode for the fonts and create your preferred look. The definitions for various printers are in the file modes.mf
For example:
% From {\tt stsmith@ll.mit.edu}, 10 May 93.
% With |fillin=0|, the diagonal of {\tt cmtt10}'s `z' is too thin.
% |blacker=.8| too thin, 2 too thick.
mode_def docutech = %\[ Xerox 8790 or 4045 (600dpi)
mode_param (pixels_per_inch, 600);
mode_param (blacker, 1);
mode_param (fillin, .1);
mode_param (o_correction, 0.9);
mode_common_setup_;
enddef;