That could be hard to do freehand. There is a KS plotter project, the WaterColorBot, which is very inexpensive and should be easy to adapt to this. Then, over-tracing and creating multiple overlapping parallel traces could be rather easily achieved.

With regard to this question they responded,

"2. There are ways to reduce the ohm rating when dry, simply rubbing the trace with a hard, smooth surface like a rounded pen cap will decrease the resistance by increasing particle to particle contacts 3. The ink can support a maximum current of about 175 mA on standard copy paper. Higher currents cause joule heating and a subsequent drop in resistance due to sintering the particles (up to around 8x decrease in resistance if controlled). Currents exceeding 400 mA may break the trace on standard copy paper. High currents can be achieved with photo paper, near 800mA. 4. Currently, the ink will only be available via rollerball pen, but this can be adapted to be used in various plotters. We will have videos and demos of this shortly. 5. Conductive adhesives will work with the ink"