Something I haven't tried (yet) but is worth a shot is to use the same ink used
in stamp pads since that is easily available and it is available in a variety of
colors.
From: "Chuck Guzis" <cclist at
sydex.com>
One solution might be to obtain the ink and pen from a
strip recorder and
fit it to the plotter. These don't dry out as quickly and can be easily
unclogged with a small cleaning wire.
Cheers,
Chuck