Pen Plotters:

This moves the pen over a piece of paper in random, vector drawing style. In order  to draw a line first the pen is positioned at the start of the line and then lower to the paper, moved in a straight line to the end point of the line, raised, and move to the begin of the next line. There are two fundamental varieties of pen plotters - flat bag plotters & drum plotters. In flat bag plotters, a sheet of paper is spread out on a table & held out by the electrostatic charge & pen moves in x-y direction on this sheet, while in drum plotters paper moves along one axis and pen moves along the other axis.

In pen plotters, plotting speed based on the acceleration and the velocity with which pen may be moved. Pen acceleration is partially a function of the mass of the plot head. There are some other kinds of devices like camera and cycolar.