It is surprinsigly hard to move paper the way a printer does it. The easiest way for DIY would be to use a continuous roll of paper and a very thin pen on a 3d printer like stepper motor, like older dot matrix printers.
>>kuon+(OP)
If it fits the quality you need, I think a plotter is actually the best option; the FOSS ones seem to just take arbitrary pens for ink and there's a fair few projects implementing open source plotters that seem to get decent results.